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Palaeeudyptes klekowskii, the best preserved penguin skeleton from the Eocene-Oligocene of Antarctica: Taxonomic and evolutionary remarks
... In recent years, several articulated skeletons have been discovered and reported on Seymour Island, contributing to our understanding of Antarctic penguin morphology (Jadwiszczak, 2012;Acosta Hospitaleche and Reguero, 2014;Jadwiszczak and Mörs, 2019). Notably, a few of these skeletons can be attributed to giant penguins. ...
... For instance, MLP 14-XI-27-84 (Anthropornis grandis) is particularly noteworthy as it is the sole specimen to preserve skull material (Acosta Hospitaleche et al., 2019b). MLP 11-II-20-07 (Palaeeudyptes klekowskii) is remarkable for its abundance of bones, including nearly complete wing bones, partial hind limbs and a coracoid (Acosta Hospitaleche and Reguero, 2014). Other significant discoveries include an articulated wing with mineralized skin for Palaeeudyptes gunnari (Acosta Hospitaleche et al., 2020) and a skeleton containing several wing bones assigned to Anthropornis sp. ...
... It's worth noting that these wing bones have also been reported in Palaeeudyptes klekowskii and P. gunnari (Acosta Hospitaleche and Reguero, 2010Reguero, , 2014. These bones in both taxa are generally stout and flat, with the wing bones of the new specimen as a similar fragmentary portion to the two previously mentioned species. ...
Eocene penguins from Seymour Island play an important role in studies related to the taxonomy and evolution of the Sphenisciformes stem group. Among these penguins, the Palaeeudyptes species are particularly noteworthy for their unusually large size and the contentious nature of their classification criteria. In this study, we describe a new penguin skeleton with a well-preserved tarsometatarsus discovered in the Upper Eocene of Seymour Island, Antarctica. The new fossil exhibits the tarsometatarsal characteristics of Palaeeudyptes but differs from two species of Palaeeudyptes previously found on Seymour Island, providing insights on the morphological diversity and evolutionary history of early penguins. We conducted normality and unimodality tests on Palaeeudyptes taxa from Seymour Island to reassess the hypothesis that size differences between the two species of this genus could be attributed to sexual dimorphism in a single species. The results revealed that size differences are unlikely due to sexual dimorphism. We also use linear discriminant analysis to evaluate the taxonomic criteria for the two Palaeeudyptes species discovered in the Antarctic region. The data showed an overlap in the size distribution, indicating weakness in the classification criteria. Reassessing previous samples and establishing an additional diagnosis based on critical anatomical features could potentially resolve this issue.
... Even though the list of penguin fossil species is much more extensive, rigorous analyses carried out over recent decades have established long synonymic lists of species and genera that are no longer considered valid. Table 1 follows the taxonomic arrangements proposed for Argentinian [63][64][65][66][67][68][69][70][71], Chilean [67,69,72,73,78,81], Peruvian [24,28,41,57,69,73], Antarctic [27,[49][50][51][52][53][54][57][58][59], New Zealand [11,17,19,20,33,38,42,48,55,60], Australian [56,67,75], and African [76,77] taxa. This compilation is essential to obtain complementary information for the discussion and the palaeoecological analysis. ...
Despite its current low diversity, the penguin clade (Sphenisciformes) is one of the groups of birds with the most complete fossil record. Likewise, from the evolutionary point of view, it is an interesting group given the adaptations developed for marine life and the extreme climatic occupation capacity that some species have shown. In the present contribution, we reviewed and integrated all of the geographical and phylogenetic information available, together with an exhaustive and updated review of the fossil record, to establish and propose a biogeographic scenario that allows the spatial-temporal reconstruction of the evolutionary history of the Sphenisciformes, discussing our results and those obtained by other authors. This allowed us to understand how some abiotic processes are responsible for the patterns of diversity evidenced both in modern and past lineages. Thus, using the BioGeoBEARS methodology for biogeographic estimation, we were able to reconstruct the biogeographical patterns for the entire group based on the most complete Bayesian phylogeny of the total evidence. As a result, a New Zealand origin for the Sphenisciformes during the late Cretaceous and early Paleocene is indicated, with subsequent dispersal and expansion across Antarctica and southern South America. During the Eocene, there was a remarkable diversification of species and ecological niches in Antarctica, probably associated with the more temperate climatic conditions in the Southern Hemisphere. A wide morphological variability might have developed at the beginning of the Paleogene diversification. During the Oligocene, with the trends towards the freezing of Antarctica and the generalized cooling of the Neogene, there was a turnover that led to the survival (in New Zealand) of the ancestors of the crown Sphenisciform lineages. Later these expanded and diversified across the Southern Hemisphere, strongly linked to the climatic and oceanographic processes of the Miocene. Finally, it should be noted that the Antarctic recolonization and its hostile climatic conditions occurred in some modern lineages during the Pleistocene, possibly due to exaptations that made possible the repeated dispersion through cold waters during the Cenozoic, also allowing the necessary adaptations to live in the tundra during the glaciations.
... The Eocene Marambio/Seymour Island (Fig. 1) penguin record includes isolated cranial elements (Table 1) with a systematic allocation restricted to the family level. On the other hand, the few incomplete skeletons described from the Eocene of Antarctica (Acosta Hospitaleche, 2016;Acosta Hospitaleche and Di Carlo, 2010;Reguero, 2010, 2014;Jadwiszczak, 2012) do not preserve the skull. ...
... The Eocene Marambio/Seymour Island (Fig. 1) penguin record includes isolated cranial elements (Table 1) with a systematic allocation restricted to the family level. On the other hand, the few incomplete skeletons described from the Eocene of Antarctica (Acosta Hospitaleche, 2016;Acosta Hospitaleche and Di Carlo, 2010;Reguero, 2010, 2014;Jadwiszczak, 2012) do not preserve the skull. ...
Associated penguin remains found in Bartonian levels of the Submeseta Formation (Seymour Island, Antarctica), including cranium and mandible, both partial tarsometatarsi, and some other fragmentary bones, are here analyzed. This specimen preserves the first cranium reliably assigned to the giant form Anthropornis grandis, and constitutes the first opportunity to taxonomically assign a cranial material to any of the Antarctic penguin species. A discussion of the diet preferences and feeding mechanisms of A. grandis is supported here by three-dimensional paleoneurological and cranial-jaw muscular reconstructions. We propose that A. grandis was a penguin with a voluminous musculature strongly attached to the neck and skull, adapted to chase and hunt fish during diving.
... gunnari; Acosta Hospitaleche and Reguero, 2010), and MLP 11-II-20-07 from DPV 13/84 (P. klekowskii; Acosta Hospitaleche and Reguero, 2014). Importantly, these skeletons include both the tarsometatarsus and humerus. ...
The fossil record of birds from Antarctica is concentrated in the James Ross Basin, located in northeast of the Antarctic Peninsula. Birds are here represented by an extensive Paleogene record of penguins (Sphenisciformes) and Cretaceous-Paleogene record of Anseriformes, followed by other groups with a minor representation (Procellariiformes, Falconiformes, and Pelagornithidae), and others previously assigned controversially to "Ratites", Threskiornithidae, Charadriiformes, Gruiformes, Phoenicopteriformes, and Gaviiformes. We provide a complete update of these records, commenting on the importance of some of these remains for the evolution of the major clades.
... Recent discoveries of partial skeletons including tarsometatarsi belonging to giant Sphenisciformes from Antarctica, Palaeeudyptes gunnari (Wiman, 1905), and P. klekowskii Myrcha et al., 1990, have shed some light onto the body plan of these intriguing birds (Acosta Hospitaleche and Reguero, 2010Reguero, , 2014. Specimens assignable to extremely large-sized penguins from the Eocene of Seymour Island, especially from the genus Palaeeudyptes Huxley, 1859, clearly outnumber those belonging to their smaller relatives (Myrcha et al., 2002;Jadwiszczak, 2006). ...
The oldest fossil record of Antarctic penguins comes from Seymour Island (Antarctic Peninsula) and dates to the Paleocene and Eocene. The Paleocene bones are extremely rare, whereas specimens from the latter epoch are numerous. Despite the recent discoveries of incomplete skeletons assignable to the giant penguins from the Eocene of Antarctic Peninsula, the reliable systematics of their smaller contemporaneous relatives, known from isolated bones, have remained dependent on the tarsometatarsus. Here, new data on the skeleton of Delphinornis larseni, the most abundant among non-giant Eocene penguins, are reported. The specimen, collected from the Submeseta Formation on Seymour Island, comprises the incomplete pelvis and numerous bones from the hind-limb skeleton, including a well-preserved (diagnostic) tarsometatarsus. The acetabular foramen is, like in larger fossil penguins, clearly smaller than the elongated ilioischiadic foramen. The area of the latter opening, not occupied by the connective-tissue sheet, supposedly accounted for one-third of the foramen. We propose that the ischiadic artery was, unlike in present-day penguins, the main blood vessel supplying most of the hind limb. The proximal fovea of the femoral head is uniquely preserved, revealing an osteological aspect of the bone-ligament interface. We surmise that the individual was similar, in terms of body size, to extant Pygoscelis papua, but was characterized by more elongate feet. In our opinion, it was probably a young bird, up to several years old.
... In addition, several characters were newly scored for Palaeeudyptes gunnari (Wiman, 1905), Palaeeu- dyptes klekowskii Myrcha, Tatur, and del Valle, 1990, andAnthropornis nordenskjoeldi Wiman, 1905, based on new speci- mens described subsequent to the original publication of these matrices. New scorings for Palaeeudyptes gunnari are based on specimen MLP 96-I-6-13 (Acosta Hospitaleche and Reguero, 2010), and new scorings for Palaeeudyptes klekowskii are based on specimen MLP 11-II-20-07 (Acosta Hospitaleche and Reguero, 2014). New scorings for Anthropornis nordenskjoeldi are based on specimens NHMUK A3355-3359. ...
Madrynornis mirandus, one of the few fossil penguins known from a nearly complete articulated skeleton, represents a key taxon for understanding the stem-crown transition in penguins. Despite the wealth of morphological character data preserved in the holotype specimen, the phylogenetic placement of this early late Miocene taxon has remained controversial. Reexamination of the Madrynornis mirandus holotype provides support for placement within the penguin crown clade. However, this placement is highly sensitive to the molecular signal and Madrynornis falls just outside the crown clade when molecular data are excluded. The neuroanatomy of Madrynornis shares many derived features with extant penguins, including an airencephalic brain shape, highly reduced bulbus olfactorius, and absence of an interaural pathway. However, the brain endocast differs from all surveyed extant species in that the eminentia sagittalis (wulst) is less caudally expanded, the tectum opticus is relatively less developed, and the flocculus is stouter and more laterally disposed. The cranial osteology and reconstructed jaw myology of Madrynornis suggest a primarily piscivorous diet, which likely characterizes the clade uniting Madrynornis, Inguza, Eudyptula, and Spheniscus.
SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP
Citation for this article: Degrange, F. J., D. T. Ksepka, and C. P. Tambussi. 2018. Redescription of the oldest crown clade penguin: cranial osteology, jaw myology, neuroanatomy, and phylogenetic affinities of Madrynornis mirandus. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1445636.
... Assuming that the humerus proportions are not sensitive to significant intraspecific variation, it seems possible to calculate an approximate length of 259.2 mm for the MLP 12-I-20-288 on the basis of the measurements taken in the co-specific MLP 11-II-20-07, and scaling its size from the width of the proximal epiphysis (Acosta Hospitaleche, 2013b; Acosta Hospitaleche and Reguero, 2014). Dimensions of the humerus MLP 12-I-20-288 are also huge in comparison with the penguin bones described so far (Acosta Hospitaleche, 2013b; Acosta Hospitaleche and Reguero, 2014;Jadwiszczak, 2006;Tambussi et al., 2006). These values are only estimates and cannot be taken as absolute. ...
Un tarsometatarsus et un humérus fragmenté d’énormes dimensions, récemment recueillis dans l’Éocène supérieur DPV 13/84 (niveau 38, Submeseta II) de la formation Submeseta de l’île Seymour (Marambio), péninsule Antarctique, ont été attribués à Palaeeudyptes klekowskii. Selon les estimations, le tarsometatarsus appartiendrait au manchot le plus grand et le plus massif décrit jusqu’à présent. Cet oiseau a été un pingouin piscivore, avec une forte capacité de plongée sous-marine pour la capture des proies. Bien que l’humérus ne soit pas un élément approprié pour les évaluations de masse corporelle ou de longueur du corps, il appartenait aussi à un énorme manchot.
Osteohistological studies allow us to obtain valuable information on different aspects related to the bone microstructure, physiology and ecology of organisms. Although the anatomy and morphology of penguin bones are well known, studies in osteohistology are still insufficient. In order to analyze the osteohistological variations between male and female adults of Pygoscelis adeliae (Aves, Spheniscidae), histological sections were prepared from various bones including appendicular (humerus, radius, ulna, carpometacarpus, femur, tibiotarsus, tarsometatarsus) and axial (vertebral and sternal ribs) elements. The results indicate that all sections showed compact tissue with reduced or absent medullary cavities and high bone density due to internal tissue compaction. Histologically, we identified three distinct tissue regions based on their bone matrix, vascular channels organization and compactions degree. Our results indicate osteohistological variations between sexes throughout the whole skeleton, including the first definitive evidence of medullary bone in the Sphenisciformes females. While the male specimen exhibited a medullary cavity characterized by an inner circumferential layer, the female displayed a medullary region without an inner circumferential layer, lower bone compaction, presence of medullary bone in all the sections, and greater development of intertrabecular spaces. These results are consistent with previous reports of medullary bone in females from other birds and provided an auxiliary criterion for sex differentiation.
To analyze the osteohistological variations between adult individuals of Pygoscelis adeliae , histological sections of the mid-level of the shaft of different bones (humerus, radius, ulna, carpometacarpus, femur, tibiotarsus, tarsometatarsus and ribs) of a female and a male, were compared. The results indicate that, at the microanatomical level, the sections present a compact tissue with a reduced (or null) medullary cavity and a high bone density resulting from the internal compaction of the tissues. At the histological level, three tissue regions, defined by their bone matrix, level of organization of the vascular channels, and the degree of compaction, can be identified. However, sexual differences and variations in the microstructure and histology along the skeleton were found in the penguin Pygoscelis adeliae . A medullary cavity defined by an inner circumferential system appears in the male, whereas in the female, a remaining medullary cavity without the development of an inner circumferential layer, a lower degree of bone compaction, the presence of medullary tissue, and intertrabecular spaces, was observed. These results are consistent with reports of medullary bone in females from other groups of birds and provided an assistant criterion for the differentiation of sexes.
Trace elements, particularly rare earth elements (REE), are widely used as proxies to reconstruct paleoenvironmental and taphonomic conditions. We traced these elements in fossil penguin bones collected along the Paleogene sequence exposed in Seymour Island (=Isla Marambio) to test them as indicators of the tectonic changes to which this region was exposed. The results indicated the contents of REE in thirteen samples of the analyzed bone tissues. The negative europium anomaly in the samples from Bartonian and Priabonian beds reflects regional events. This signal coincides in time with the opening of the Drake Passage, and with the tectonic changes that occurred between the end of the Eocene and the beginning of the Oligocene, between the western margin of South America and the Antarctic Peninsula.
HISTORY OF THE PALEORNITHOLOGICAL STUDIES IN THE MUSEO DE LA PLATA. The first studies on fossil birds in the Museo de La Plata were carried out since the last decade of the 19th century. These were isolated studies, which did not increase their frequency or intensity until the beginning of the 20th century. Since then, an increasing amount and thematic deepening led to the specificity that today characterizes the scientific works around the world. From that moment, the Museo de La Plata was consolidated as a training center for paleontologists who established themselves in other institutions forming new work teams.
Key words. Fossil birds. History. Paleornithologists. La Plata Museum. La Plata National University.
There is strong molecular support for a clade including the non-monophyletic “Pelecaniformes” except the Phaethontiformes (tropicbirds), as well as the Sphenisciformes (penguins), Gaviiformes (loons), Procellariiformes (tubenoses), and the taxa of the non-monophyletic “Ciconiiformes”. This “waterbird clade” was termed Aequornithes, and the Phaethontiformes result as close relatives of it in current analyses. The fossil record shows that the Aequornithes have a very long evolutionary history. Stem group representatives of the Sphenisciformes date back to the mid-Paleocene and stem group Procellariiformes may have already existed in the Late Cretaceous. The early evolution of the Aequornithes remains, however, poorly understood. The skeletal morphology of early Eocene stem group representatives of the Threskiornithidae, for example, is markedly different from that of coeval Sphenisciformes, which indicates a long evolutionary separation of the lineages leading to these two taxa already by that time. It is also elusive where the stem species of the Aequornithes occurred, although this may well have been on one of the southern continents.
Antarctica underwent a complex evolution over the course of the Cenozoic, which influenced the history of the Earth’s climate system. The Eocene-Oligocene boundary is a divide of this history when the ice-free ‘greenhouse world’ transitioned to the ‘icehouse’ with the glaciation of Antarctica.
Prior to this, Antarctica experienced warm climates, peaking during Early Eocene when tropical-like conditions existed at the margins of the continent where geological evidence is present. Climate signals in the geological record show that the climate then cooled, but not enough to allow the existence of significant ice until the latest Eocene. Glacial deposits from several areas around the continental margin indicate that ice was present by the earliest Oligocene. This matches the major oxygen isotope positive shift captured by marine records. On land, vegetation was able to persist, but the thermophylic plants of the Eocene were replaced by shrubby vegetation with the southern beech Nothofagus, mosses and ferns, which survived in tundra-like conditions. Coupled climate–ice sheet modelling indicates that changing levels of atmospheric CO2 controlled Antarctica’s climate and the onset of glaciation. Factors such as mountain uplift, vegetation changes, ocean gateway opening and orbital forcing all played a part in cooling the polar climate, but only when CO2 levels reached critical thresholds was Antarctica tipped into an icy glacial world.
The middle-late Eocene of Antarctica was characterized by dramatic change as the continent became isolated from the other southern landmasses and the Antarctic Circumpolar Current formed. These events were crucial to the formation of the permanent Antarctic ice cap, affecting both regional and global climate change. Our best insight into how life in the high latitudes responded to this climatic shift is provided by the fossil record from Seymour Island, near the eastern coast of the Antarctic Peninsula. While extensive collections have been made from the La Meseta and Submeseta formations of this island, few avian taxa other than penguins have been described and mammalian postcranial remains have been scarce. Here, we report new fossils from Seymour Island collected by the Antarctic Peninsula Paleontology Project. These include a mammalian metapodial referred to Xenarthra and avian material including a partial tarsometatarsus referred to Gruiformes (cranes, rails, and allies). Penguin fossils (Sphenisciformes) continue to be most abundant in new collections from these deposits. We report several penguin remains including a large spear-like mandible preserving the symphysis, a nearly complete tarsometatarsus with similarities to the large penguin clade Palaeeudyptes but possibly representing a new species, and two small partial tarsometatarsi belonging to the genus Delphinornis. These findings expand our view of Eocene vertebrate faunas on Antarctica. Specifically, the new remains referred to Gruiformes and Xenarthra provide support for previously proposed, but contentious, earliest occurrence records of these clades on the continent.
Numerous skeletal remains recovered in situ from the late early to middle Paleocene Takatika Grit of Chatham Island, New Zealand, are among the oldest known fossils attributed to the penguin clade (Aves, Sphenisciformes). They represent a new medium-sized taxon, for which we erect a new genus and species, and a second, notably larger form. These new penguins are analysed in a parsimony and Bayesian framework using an updated and revised phylogenetic matrix, based on morphological and molecular characters, and interpreted as among the most basal of known sphenisciforms, closely related to Waimanu. While sharing numerous characteristics with the earliest wing-propelled divers, the novel taxon records the oldest occurrence of the characteristic penguin tarsometatarsus morphology. These ancient Chatham Island representatives add to a growing number and increased morphological diversity of Paleocene penguins in the New Zealand region, suggesting an origin for the group there. With their addition to other Paleocene penguins, these taxa reveal that sphenisciforms rapidly diversified as non-volant piscivores in the southern oceans following the end-Cretaceous mass extinction. They also provide further evidence for the hypothesis that their origin predates the Paleocene. This implies that stem Sphenisciformes and their sister group, the Procellariiformes, both originated in, and so may be expected to occur in, the Late Cretaceous.
Numerous skeletal remains recovered in situ from the late early to middle Paleocene Takatika Grit of Chatham Island, New Zealand, are among the oldest known fossils attributed to the penguin clade (Sphenisciformes). The penguin fossils are represented by several specimens, two of which were subjected to X-ray computed tomography and virtually reconstructed in three dimensions. Morphologies of selected elements were compared to those of extinct and extant bird relatives. Additional morphological character scoring of the fossils was conducted, which was assimilated into an updated phylogenetic matrix of Sphenisciformes to consider the fossils in the context of an evolutionary framework. As a medium-sized, novel penguin taxon, these fossils are phylogenetically more derived than Waimanu and recovered in a basal position in Sphenisciformes. Interpreted as one of the most primitive known wing-propelled divers amongst Sphenisciformes morphologies observed in these fossils are consistent with a model of penguin evolution in which early penguins diverged from volant ancestors and specialised for the aquatic environment. These fossils are thus of significant relevance to the understanding of archaic penguins, as well as early neoavian waterbird evolution, and neornithine radiation in the aftermath of the K/ Pg mass extinction. This novel taxon adds to the growing number of Paleocene penguins, and supports the hypothesis that the origin of the penguin clade may be older than molecular divergence estimates of the middle Paleocene.
One of the notable features of penguin evolution is the occurrence of very large species in the early Cenozoic, whose body size greatly exceeded that of the largest extant penguins. Here we describe a new giant species from the late Paleocene of New Zealand that documents the very early evolution of large body size in penguins. Kumimanu biceae, n. gen. et sp. is larger than all other fossil penguins that have substantial skeletal portions preserved. Several plesiomorphic features place the new species outside a clade including all post-Paleocene giant penguins. It is phylogenetically separated from giant Eocene and Oligocene penguin species by various smaller taxa, which indicates multiple origins of giant size in penguin evolution. That a penguin rivaling the largest previously known species existed in the Paleocene suggests that gigantism in penguins arose shortly after these birds became flightless divers. Our study therefore strengthens previous suggestions that the absence of very large penguins today is likely due to the Oligo-Miocene radiation of marine mammals.
New remains from the La Meseta (Thanetian – Lutetian) and Submeseta (Lutetian – Rupelian) formations (Seymour Island, Antarctica) are tentatively assigned to Diomedeidae and Procellariidae (Procellariiformes). Based on the fossil record and several analyses that attempt to explain the evolutionary patterns of Diomedeidae, Notoleptos giglii gen. et sp. nov., based on a small tarsometatarsus, was an ancestral form that lived in Antarctica before the rise of large-sized albatrosses. Subsequent environmental cooling since the late Oligocene could have selected against small body size, to the detriment of small-sized albatrosses like Notoleptos, thus favoring large body size and setting the stage for the development of the specialized albatross flight.
ZooBank ID (LSID): urn:lsid:zoobank.org:pub:C8D9C862-1536-4EA3-8A76-70903AA75639
Acosta Hospitaleche, C. & Olivero, E., April 2016. Re-evaluation of the fossil penguin Palaeeudyptes gunnari from the Eocene Leticia Formation, Argentina: additional material, systematics and palaeobiology. Alcheringa 40, xx–xx. ISSN 0311-5518 Eocene penguins are known mostly from Antarctic specimens. A previously documented partial skeleton consisting of a pelvis, femur, tibiotarsus and fibula, from the middle Eocene Leticia Formation, Tierra del Fuego Province, Argentina, has been prepared and re-described. Re-analysis favours assignment to Palaeeudyptes gunnari, a species widely recorded in the Eocene of Antarctica. A new isolated coracoid belonging to an indeterminate species reveals new information about diving kinematics and swimming abilities. Palaeobiological attributes and morphology of the fossils indicate that both specimens belonged to large penguins with poor diving capability and wing propulsion systems similar to those of extant taxa. These penguin remains are the only vertebrate fossils thus far recorded from the Leticia Formation, and provide important insights into the relationships of South American and Antarctic penguins during the Paleogene. The presence of Palaeeudyptes in Argentina supports an Eocene connection between the South American and Antarctic penguin faunas. Carolina Acosta Hospitaleche [[email protected]/* */], CONICET. División Paleontología Vertebrados, Museo de La Plata Paseo del Bosque s/n, 1900 La Plata, Facultad de Ciencias Naturales y Museo, UNLP, Argentina; Eduardo Olivero [[email protected]/* */], CONICET. Centro Austral de Investigaciones Científicas (CADIC-CONICET), B. Houssay 200, 9410 Ushuaia, Tierra del Fuego, Argentina.
The new remains of Gaviiformes collected from the Maastrichtian Sandwich Bluff Member (López de Bertodano Formation in Vega Island), the Maastrichtian Klb 9 (López de Bertodano Formation in Seymour Island), the Maastrichtian Snow Hill Formation (Vega Island), and the Ypresian Submeseta Formation (Seymour Island), Antarctica, are described. A specialized foot-propelled diving morphology is already present in the Antarctic Polarornis gregorii, the Chilean Neogaeornis wetzelli and the new specimens here reported, suggesting that such diving skills were developed at least since the Upper Cretaceous. The occurrence of Gaviiformes in the Southern Hemisphere during the Upper Cretaceous–lower Eocene times is consistent with recent phylogenetic proposals relating this group to Sphenisciformes and Procellariiformes, birds already recorded in Antarctica. The fossil record also supports the idea that the hemisphere displacement observed in Gaviiformes could be a response to increasing competition for resources with Sphenisciformes. The phylogenetic proximity of penguins and loons plus their similar trophic behavior, suggest that competitive exclusion could have triggered the gaviiform migration to the Northern Hemisphere and explain their extinction from Southern continents.
This study presents the first record of Eocene birds from the western margin of southernmost South America. Three localities in Magallanes, southern Chile, have yielded a total of eleven bird remains, including Sphenisciformes (penguins) and one record tentatively assigned to cf. Ardeidae (egrets). Two different groups of penguins have been recognized from these localities. The first group is similar in size to the smallest taxa previously described from Seymour Island, Marambiornis Myrcha et al., 2002, Mesetaornis Myrcha et al., 2002, and Delphinornis Wiman, 1905. The second recognized group is similar in size to the biggest taxa from Seymour Island; based on the available remains, we recognize the genus Palaeeudyptes Huxley, 1859, one of the most widespread penguin genera in the Southern Hemisphere during the Eocene. The stratigraphic context of the localities indicates a certain level of correlation with the geological units described on Seymour Island. The newly studied materials cast more light on the paleobiogeography of the group, extending the known ranges to the South American continent. In addition to the newly discovered birds, the presence of several taxa of elasmobranchs previously recovered exclusively from Eocene beds in the Southern Hemisphere help to clarify the age of the studied localities, widely discussed during the last decades. This paper verifies the presence of extensive Eocene sedimentary successions with fossil vertebrates along the western margin of southern South America, contrary to the previous assumption that such a record is lacking in Chile.
Defining species boundaries, due to morphological variation, often represents a significant challenge in paleozoology. In this paper we report results from multi- and univariate data analyses, such as enhanced clustering techniques, principal coordinates ordination method, kernel density estimations and finite mixture model analyses, revealing some morphometric patterns within the Eocene Antarctic representatives of Palaeeudyptes penguins. These large-sized birds were represented by two species, P. gunnari and P. klekowskii, known mainly from numerous isolated bones. Investigations focused on tarsometatarsi, crucial bones in paleontology of early penguins, resulted in a probability-based framework allowing for the "fuzzy" partitioning the studied specimens into two taxa with partly overlapping size distributions. Such a number of species was supported by outcomes from both multi- and univariate studies. In our opinion, more reliance should be placed on the quantitative analysis of form when distinguishing between species within the Antarctic Palaeeudyptes.
Three skeletons collected from the late Oligocene Kokoamu Greensand of New Zealand are among the most complete Paleogene penguins known. These specimens, described here as Kairuku waitaki, gen. et sp. nov., and Kairuku grebneffi, sp. nov., reveal new details of key elements of the stem penguin skeleton associated with underwater flight, including the sternum, flipper, and pygostyle. Relative proportions of the trunk, flippers, and hind limbs can now be determined from a single individual for the first time, offering insight into the body plan of stem penguins and improved constraints on size estimates for ‘giant’ taxa. Kairuku is characterized by an elongate, narrow sternum, a short and flared coracoid, an elongate narrow flipper, and a robust hind limb. The pygostyle of Kairuku lacks the derived triangular cross-section seen in extant penguins, suggesting that the rectrices attached in a more typical avian pattern and the tail may have lacked the propping function utilized by living penguins. New materials described here, along with re-study of previously described specimens, resolve several long-standing phylogenetic, biogeographic, and taxonomic issues stemming from the inadequate comparative material of several of the first-named fossil penguin species. An array of partial associated skeletons from the Eocene–Oligocene of New Zealand historically referred to Palaeeudyptes antarcticus or Palaeeudyptes sp. are recognized as at least five distinct species: Palaeeudyptes antarcticus, Palaeeudyptes marplesi, Kairuku waitaki, Kairuku grebneffi, and an unnamed Burnside Formation species.
Penguins are by far the most dominant group of marine vertebrates in the
Eocene La Meseta Formation (Seymour Island, Antarctica). We analysed the penguin
fauna recovered there from both a systematic and a biostratigraphic point of view. We have
added two new species (Tonniornis mesetaensis and T. minimum) and have defined a
biostratigraphic unit, the Anthropornis nordenskjoeldi Biozone. This interval of strata,
easily distinguishable by the numerous occurrence of penguin bones and the phosphatic
brachiopod Lingula, is located nearly 30–35 m below the top of the 145 m-thick Submeseta
Allomember. The highest morphological and taxonomic penguin diversity living
sympatrically (organisms that live simultaneously in the same place), including giant and
tiny species, is documented in this interval. Fossil penguins bones studied in this paper,
recovered from rocks interpreted as shallow-marine deposits, accumulated between
34.2 and 36.13 Ma (late Late Eocene).
During the past two decades, geological explorations of the James Ross Basin,
Weddell Sea, have revealed that this basin, located off the northeast tip of the
Antarctic Peninsula (West Antarctica), contains one of the most important
records of Late Cretaceous and Early Paleogene life in the Southern Hemisphere.
The early explorer and scientist Otto Nordenskjöld (1905, p. 252), leader of the
Swedish South Polar Expedition, envisioned the paleontologic and biogeographic
importance of this basin “… where, maybe, many animals and plants were first
developed that afterwards found their way as far as to northern lands”. These
discoveries have not only provided new insights into the geologic history of
Antarctica, but they have also provided answers to questions about life in Southern
Hemisphere that have puzzled naturalists since Charles Darwin’s voyage on HMS
Beagle. The sedimentary sequence exposed in the James Ross Basin comprises a thick
section of Coniacian, Turonian, Campanian, Maastrichtian, Paleocene, Eocene,
and probably earliest Oligocene. They form the only marine sequence of this age
interval that crops out in Antarctica. The high-latitude biota contained in both the
Cretaceous and Paleogene beds is unusually rich and diverse and rivaled only by
that from New Zealand and southeastern Australia. After the Swedish South Polar Expedition (1901–1903), more than 40 years passed before the basin was scientifically visited again, this time by members of the Falkland Islands Dependencies Survey (now the British Antarctic Survey). The establishment of the Argentine station Marambio on Seymour Island in 1969 initiated the modern phase of geologic and paleontologic studies in the James Ross Basin. The view that Antarctica and South America were connected by a long causeway between the West Antarctica (WANT) and southern South America in the
Late Cretaceous through the late Paleocene, and that terrestrial vertebrates were
able to colonize new frontiers using this physiographical feature, is almost
certainly correct. One of the most intriguing palaeobiogeographical phenomena
involving the last phase of the breakup of the supercontinent Gondwana concerns
the close similarities and, in most cases, inferred sister-group relationships of a
number of terrestrial vertebrate taxa recovered from uppermost Cretaceous and
Paleogene deposits of Antarctic Peninsula (West Antarctica) and southern SouthAmerica (Magellanic Region and Patagonia). Dispersion of extinct vertebrates between South America and Australia across Late Cretaceous land bridges involving WANT predicts their presence during that interval on the latter. However, although knowledge of Late Cretaceous vertebrates from West Antarctica (and the Antarctic Peninsula) is still severely limited, it has expanded substantially over the last two decades and includes discoveries of avian and non-avian dinosaurs. Plants and small- to medium-sized, obligate terrestrial mammals (e.g., marsupials and meridiungulates) gained broad distribution across West Antarctica land mass prior to fragmentation and were isolated on the Antarctic Peninsula before the end of the Paleocene. From an evolutionary perspective the close relationships between terrestrial taxa found in the James Ross Basin are difficult to accommodate because, by the beginning of the Late Cretaceous (99.6 Ma), the major Gondwanan continental blocks (South America, Africa, Antarctica, Mad agascar, the Indian subcontinent,
and New Zealand–Australia) were well into the process of breakup and dispersion.
This paper deals with the hypothesis that the Antarctic Peninsula linked South
America and West Antarctica in the Late Cretaceous until the beginning of the
Paleogene and we review here through the plant and vertebrate fossil taxa the
paleogeographical evolution of the southern continents and oceans for both earlier
and later time intervals. This communication aims to explain the geological/
geophysical problems inherent in the hypothesis and to explore the consequences
for the biogeographical distributions of marine and terrestrial vertebrate faunas in
West Antarctica.
Superimposition methods for comparing configurations of landmarks in two or more specimens are reviewed. These methods show
differences in shape among specimens as residuals after rotation, translation, and scaling them so that they align as well
as possible. A new method is presented that generalizes Siegel and Benson's (1982) resistant-fit theta-rho analysis so that
more than two objects can be compared at the same time. Both least-squares and resistant-fit approaches are generalized to
allow for affine transformations (uniform shape change). The methods are compared, using artificial data and data on 18 landmarks
on the wings of 127 species of North American mosquitoes. Graphical techniques are also presented to help summarize the patterns
of differences in shape among the objects being compared.
The fossil record of the Antarctic penguins is dated to the late Paleocene of Seymour (Marambio) Island, but the largest sphenisciforms, genera Anthropornis and Palaeeudyptes, originate from the Eocene La Meseta Formation. Here, the most complete large-scale reconstruction of a limb skeleton (a whole wing and a partial hind leg) of a Paleogene Antarctic penguin is reported. All bones are attributable to a single individual identified as Anthropornis sp. The comparative and functional analyses of the material indicate that this bird was most probably well-adapted to land and sea while having a number of intriguing features. The modern-grade carpometacarpal morphology is unique among known Eocene Antarctic species and all but one more northerly taxa.
A new species of Early Tertiary fossil penguin from Seymour Island is described on the basis of tarsometartarsi from the collection acquired during the Argentinian-Polish field party of 1985. Palaeeudyptes klekowskii sp. nov. is bigger than earlier described species of this genus from the same locality. Information is given on the new collection of fossil penguin bones, a large part of which was found in one horizon of Unit III of the La Meseta Formation. The collection also includes much of the accompanying invertebrate and vertebrate fauna.
The first articulated skeleton of a penguin from the late Eocene of Antarctica is described. MLP 96-I-6-13 comes from the upper Submeseta Allomember (La Meseta Formation) of Isla Marambio (locality DPV 10/84). The significance of this finding in the context of the Anthropornis nordenskjoeldi biozone is discussed. An osteologic description of the recovered elements and a brief discussion of its systematic determination are provided. MLP 96-I-6-13 is the first articulated skeleton with sure specific assignment to Palaeeudyptes gunnari (Wiman, 1905), a species previously known only through isolated tarsometatarsi and included in the groups of Wiman.
Penguin bones from the La Meseta Formation (Seymour Island, Antarctic Penin− sula) are the only record of Eocene Antarctic Sphenisciformes. Being an abundant compo− nent of the youngest unit of the formation (Telm7), they are not so common in earlier strata. Here, I present the oldest penguin remains from the La Meseta Formation (Telm1–Telm2), often bearing close resemblance to their counterparts from younger units. Addressing the recent findings in fossil penguin systematics, I suggest there is too weak a basis for erecting new Eocene Antarctic taxa based on non−tarsometatarsal elements of penguin skeletons, and considering Oligocene species part of the studied assemblage. Finally, I conclude if the common ancestor of extant Sphenisciformes lived in the Eocene Antarctic (as suggested re− cently), penguins referred to Delphinornis seem to be prime candidates to that position.
Skeletal remains of penguins from the Eocene La Meseta Formation (Seymour Is− land, Antarctica) constitute the only extensive fossil record of Antarctic Sphenisciformes. No articulated skeletons are known, and almost all fossils occur as single isolated elements. Most of the named species are based on tarsometatarsi (for which the taxonomy was revised in 2002). Here, 694 bones (from the Polish collection) other than tarsometatarsi are reviewed, and allocated to species. They confirm previous conclusions and suggest that ten species grouped in six genera are a minimal reliable estimate of the Eocene Antarctic penguin diver− sity. The species are: Anthropornis grandis, A. nordenskjoeldi, Archaeospheniscus wimani, Delphinornis arctowskii, D. gracilis, D. larseni, Marambiornis exilis, Mesetaornis polaris, Palaeeudyptes gunnari and P. klekowskii. Moreover, diagnoses of four genera (Anthropornis, Archaeospheniscus, Delphinornis and Palaeeudyptes) and two species (P. gunnari and P. klekowskii) are supplemented with additional, non−tarsometatarsal features. Four species of the smallest penguins from the La Meseta Formation (D. arctowskii, D. gracilis, M. exilis and M. polaris) seem to be the youngest taxa within the studied assemblage – their remains come exclusively from the uppermost unit of the formation. All ten recognized species may have co−existed in the Antarctic Peninsula region during the Late Eocene epoch. Key wo r d s: Antarctica, La Meseta Formation (Eocene), paleontology (penguins), taxon− omy.
Penguin bones from the Eocene La Meseta Formation (Seymour Island, Antarctic Peninsula) constitute the only extensive fossil record of Antarctic Sphenisciformes. Here, we synonymize some of the recognized genera (Anthropornis with Orthopteryx, Delphinornis with Ichtyopteryx) and species (Anthropornis nordenskjoeldi with Orthopteryx gigas, Delphinornis gracilis with Ichtyopteryx gracilis). Moreover, we suggest that Antarctic species of Anthropornis and Palaeeudyptes, so-called giant penguins, may in fact comprise only one species each instead of two, based on evidence of well-marked sexual dimorphism. We also present new estimates of body mass based on femora testifying to the impressive scope of interspecific body-size variation in Eocene Antarctic penguins.
The penguin skeleton studied here constitutes the fourth partial skeleton found in Patagonia, and the third one with an associated humerus and tarsometatarsus. The finding of this partial skeleton identified with certainty as Palaeospheniscus patagonicus Moreno and Mercerat, 1891 (Aves, Sphenisciformes) allows the first description of elements other than the tarsometatarsus. The material comes from the basal sector
of the Gaiman Formation (Early Miocene), located along the Atlantic coast of Chubut Province, south of awson city. This unit comprises a succession of shales, fine tuffs, sandstones, tuffaceous sandstones, and coquinas deposited in a shallow marine environment. These beds contain abundant marine vertebrates (sharks, dolphins, rays, birds), mollusk casts, and oyster beds. The skeleton includes: rostrum, two thoracic vertebrae, right coracoid without the distal end, left humerus, right femur, right tarsometatarsus, left fragmentary scapula, left coracoid, left radius without the distal end, proximal portion of left ulna, proximal end of left femur, and preacetabular part of the synsacrum. P. patagonicus would have
been a medium-sized penguin weighing about 5 kg that inhabited the breeding colonies established in the nearby Bryn Gwyn area during the early Miocene. Despite the abundance of penguin remains known for Argentina, and the fact that they are among the birds with a better fossil record, this skeleton is an exceptional case. This finding allows a readjustment of the taxonomic criteria applicable to fossil and living species.
Göhlich, U.B. 2007. The oldest fossil record of the extant penguin genus Spheniscus—a new species from the Miocene of Peru. Acta Palaeontologica Polonica 52 (2): 285–298. Described here is a partial postcranial skeleton and additional disarticulated but associated bones of the new fossil pen− guin Spheniscus muizoni sp. nov. from the latest middle/earliest late Miocene (11–13 Ma) locality of Cerro la Bruja in the Pisco Formation, Peru. This fossil species can be attributed to the extant genus Spheniscus by postcranial morphology and is the oldest known record of this genus. Spheniscus muizoni sp. nov. is about the size of the extant Jackass and Magellanic penguins (Spheniscus demersus and Spheniscus magellanicus). Beside Spheniscus urbinai and Spheniscus megaramphus it is the third species of Spheniscus represented in the Pisco Formation. This study contains morphological comparisons with Tertiary penguins of South America and with most of the extant penguin species.
Eocene penguin remains from Seymour Island (Antarctica) are so far the old− est−known record of extinct Sphenisciformes. Rich Argentine and Polish collections of pen− guin bones from the La Meseta Formation are taxonomically revised on tarsometatarsal morphology. Two genera and four species are erected: Mesetaornis polaris gen. et sp. n., Marambiornis exilis gen. et sp. n., Delphinornis arctowskii sp. n. and D. gracilis sp. n. Moreover, the diagnoses of already described species: Anthropornis nordenskjoeldi, A. grandis, Palaeeudyptes klekowskii, P. gunnari, Archaeospheniscus wimani and Delphi− nornis larseni are revised as well. Gradual cooling of climate, changes of environment and trophic relationships, that lasted several millions years, were most probably responsible for the intense speciation and taxonomic diversification of the Middle–Late Eocene La Meseta penguins.
2007. A new Miocene penguin from Patagonia and its phylogenetic relationships. Acta Palaeontologica Polonica 52 (2): 299–314. We describe a new medium−sized penguin, Madrynornis mirandus gen. et sp. nov., from the early late Miocene Puerto Madryn Formation, Chubut Province, Argentina. Although it is evident that extant and fossil penguins form a remarkably homogeneous family of birds, Spheniscidae, their within−group phylogenetic relationships are less obvious. In order to identify the phylogenetic position of the new taxon, we conducted a phylogenetic analysis using 44 osteological charac− ters sampled from 14 representative species of all living genera and five fossil species of Spheniscidae. The family is clearly monophyletic and Madrynornis mirandus is closely related to living taxa. Our phylogenetic interpretation is con− gruent with biostratigraphic data, with Paraptenodytes from the early Miocene (about 20 Ma) located at the base of the Spheniscidae. Classically, two basic tarsometatarsal types were recognized (one for pre−Miocene and the other for the post−Miocene penguins) based on the pattern of the proximal foramina and the hypotarsus. Madrynornis mirandus exhib− its an arrangement of the proximal foramina and a degree of metatarsals fusion similar to that in the living forms, although its elongation index (total length/proximal width) is reminiscent of the extinct Paraptenodytes (a penguin historically rec− ognized as a pre−Miocene form, coming from the early Miocene of Argentina). Madrynornis reveals that the two basic tarsometatarsal types co−existed among Miocene penguins.
We present the first phylogenetic analysis of the Sphenisciformes that extensively samples fossil taxa. Combined analysis of 181 morphological characters and sequence fragments from mitochondrial and nuclear genes (12S, 16S, COI, cytochrome b , RAG‐1) yields a largely resolved tree. Two species of the New Zealand Waimanu form a trichotomy with all other penguins in our result. The much discussed giant penguins Anthropornis and Pachydyptes are placed in two clades near the base of the tree. Stratigraphic and phylogenetic evidence suggest that some lineages of penguins attained very large body size rapidly and early in the clade's evolutionary history. The only fossil taxa that fall inside the crown clade Spheniscidae are fossil species assigned to the genus Spheniscus . Thus, extant penguin diversity is more accurately viewed as the product of a successful radiation of derived taxa than as an assemblage of survivors belonging to numerous lineages. The success of the Spheniscidae may be due to novel feeding adaptations and a more derived flipper apparatus. We offer a biogeographical scenario for penguins that incorporates fossil distributions and paleogeographic reconstructions of the Southern continent's positions. Our results do not support an expansion of the Spheniscidae from a cooling Continental Antarctica, but instead suggest those species that currently breed in that area are the descendants of colonizers from the Subantarctic. Many important divergence events in the clade Spheniscidae can instead be explained by dispersal along the paths of major ocean currents and the emergence of new islands due to tectonic events.
© The Willi Hennig Society 2006.
Aptian to Pliocene time-series of X-ray fluorescence data from the Antarctic Peninsula are used to assess the degree of chemical weathering and maturity of sediments deposited prior, and subsequent to the establishment of glaciation in West Antarctica. A continuous palaeoclimatic signal is inferred from comparing the results with previously published palaeotemperature and palaeobotanical data. Aptian–Cenomanian (warm/cool), and Santonian–Early Paleocene (warm/cold) cycles were followed by the global Late Paleocene–Early Eocene climatic optimum. Subsequent steady decline in temperatures resulted in glacial conditions in the northern Antarctic Peninsula by Early Oligocene time. Under alternating Cenozoic frigid/cold climates and in sedimentary regimes dominated by physical weathering, geochemical signatures were primarily indicative of provenance. The development of Cretaceous arboreal vegetation in the northern Antarctic Peninsula can be correlated with the major climatic cycles.
In general terms, the shape of an object, data set, or image can be de fined as the total of all information that is invariant under translations, rotations, and isotropic rescalings. Thus two objects can be said to have the same shape if they are similar in the sense of Euclidean geometry. For example, all equilateral triangles have the same shape, and so do all cubes. In applications, bodies rarely have exactly the same shape within measure ment error. In such cases the variation in shape can often be the subject of statistical analysis. The last decade has seen a considerable growth in interest in the statis tical theory of shape. This has been the result of a synthesis of a number of different areas and a recognition that there is considerable common ground among these areas in their study of shape variation. Despite this synthesis of disciplines, there are several different schools of statistical shape analysis. One of these, the Kendall school of shape analysis, uses a variety of mathe matical tools from differential geometry and probability, and is the subject of this book. The book does not assume a particularly strong background by the reader in these subjects, and so a brief introduction is provided to each of these topics. Anyone who is unfamiliar with this material is advised to consult a more complete reference. As the literature on these subjects is vast, the introductory sections can be used as a brief guide to the literature.
Isolated and fragmented jaws, a single basioccipitale and vertebrae of the Gadiformes, indeterminate family and genus, are described form Eocene sediments of the La Meseta Formation, Seymour Island, Antarctic Peninsula. Based on the dentition and other characters of both jaws they are assigned an informal name of "Mesetaichthys'. The remaining isolated bones belong probably to the same form. -Authors
La Meseta Formation is a discontinuity bounded sedimentary unit which crops out on Marambio (Seymour) and Cockburn islands, approximately 100 km SE of the northern tip of the Antarctic Peninsula. The base of this unit is a diachronous surface which intersects all other older units of the island. Along this surface the hiatus increases towards the West. The top is another unconformity below the glacimarine post-Pliocene deposits of the Weddell Formation. The lenticular geometry and the architecture of the internal units was interpreted as filling an incised valley, eroded on an emerging platform after the tilting of the Marambio Group and the Cross Valley Formation beds. The La Meseta Formation has a thickness of 620 m on Marambio island and was divided into three members (I to III from base to top). Nevertheless, the lithosome architecture, the relationships between facies and the sedimentary palaeoenvironments are better explained using an allostratigraphic scheme. The La Meseta alloformation is 720 m thick and was divided into six allomembers, each representing a sedimentary stage. Due to the regional importance of the unconformities which limit this unit, it is interpreted that it also represents a depositional sequence. The stratigraphy, structural characteristics and facies architecture of the La Meseta Aloformation are better explained considering a tectonic/erosive mixed origin of the unconformities and thus a tectonic control for the history of the valley is proposed.
KEY WORDS. Stratigraphy. La Meseta Formation. Eocene. Antarctica.
Resumen. ESTRATIGRAFÍA DE LA FORMACION LA MESETA, ISLA MARAMBIO (SEYMOUR), ANTÁRTIDA. La Formación La Meseta es una unidad sedimentaría limitada por discordancias que aflora en las islas Marambio y Cockburn, ubicadas aproximadamente a 100 km al sudeste del extremo norte de la Península Antártica. La base de esta formación es una superficie diacrónica que intersecta a todas las unidades más antiguas de la isla. A lo largo de esta superficie el hiato se incrementa hacia el oeste. El techo de la unidad es otra discordancia por debajo del depósito glacimarino post-Plioceno de la Formación Weddell. La geometría lenticular y la arquitectura de las unidades internas fueron interpretadas como producto del relleno de un valle incidido, labrado sobre una plataforma emergente con posterioridad al volcamiento de las capas del Grupo Marambio y de la Formación Cross Valley. La Formación La Meseta presenta en la isla Marambio un espesor de 620 m y ha sido subdividida en tres miembros (I a III de base a techo). Sin embargo, la arquitectura de los litosomas, las relaciones entre facies y los paleoambientes sedimentarios son mejor interpretados utilizando un esquema de subdivisión aloestratigráfico. La aloformación La Meseta tiene un espesor de 720 m y fue subdividida en seis alomiembros cada uno de los cuales representa una etapa de sedimentación. Dada la importancia regional de las discordancias que limitan esta unidad se interpreta que la misma corresponde también a una secuencia depositacional. La estratigrafía, características estructurales y arquitectura de las facies de la aloformación La Meseta son explicadas de un modo más armónico considerando un origen mixto, tectónico-erosivo, de las discordancias y por lo tanto se propone un control tectónico en la historia del valle.
PALABRAS CLAVE. Estratigrafía. Formación La Meseta. Eoceno. Antártida.
The importance of the tarsometatarsus in the systematic studies of birds, and particularly of penguins, is well established. To determine the diagnostic value of metric characters of the tarsometatarsus, a multivariate analysis was performed using 8 variables measured in 46 adults specimens. The results allowed to distinguish the different morphological patterns in the living and fossil Patagonian penguins, making possible to discriminate which variables are systematically significant.
The morphological variation presents in the penguin tarsometatarsi from Pisco Formation (Miocene-Pliocene) from Peru assigned to Spheniscus Brisson, 1760 is analyzed. Metrics and geometric techniques to quantify the diversity present in each of the nine sites localities at the south-central coast were applied. A comparative description of Spheniscus and its Miocene morphologically closest genus Palaeospheniscus Moreno and Mercerat, 1891 is also provided. They together constitute the penguin avifauna of the Miocene of Peru. The results allow us to recognize that the intra-specific diversity is at the same level of variation than the inter-specific one. At least five species of Spheniscus are hereby recognized: Spheniscus urbinai Stucchi 2002, S. megaramphus Stucchi, Urbina and Giraldo 2003, S.muizoni Göhlich 2007 and two innominated species. Each one of these species transgresses the boundaries between the localities, being represented in more than one locality. It was not possible to distinguish S. chilensis Emslie and Guerra Correa, 2003 from its tarsometatarso. The presence of six species in this unit could be related to the establishment of cold water and the advent of favorable conditions for diversification.
An articulated skeleton coming from An articulated skeleton coming from sediments of the Gaiman Formation (Early Miocene), Chubut Province, Argentina assigned to Palaeospheniscus biloculata (Simpson) nov. comb, is described. The original diagnosis of this genus and species is emended. Eretiscus tonnii (Simpson), Palaeospheniscus bergi Moreno and Mercerat, P. patagonicus Moreno and Mercerat and P. biloculata (Simpson) nov. comb, are included in the "Palaeospheniscinae" group, whose distribution is restricted to the Neogene of South America.
Incised-valley compound fills are currently modeled in terms of multiple cycles of relative sea-level fall and rise. In contrast, the Eocene La Meseta Formation from Seymour Island is a shelf-valley geometrically compound fill, the development of which was governed mainly by local subsidence along fault-controlled valley margins and associated amplified tidal circulation. The valley contains a ≥330-m-thick, festoonlike stack of transgressive-regressive, marine-estuarine cycles affected by slumping and sliding, growth faulting, and warping near the margins. Aggradational stacking of the transgressive-regressive cycles reflects transgressions initiated or enhanced by episodic subsidence of the valley floor, whereas sequence boundaries record those base-level falls having rates that exceeded the rate of valley-floor subsidence. Compound fills, particularly those of shelf-valley systems developed along active basement structures, should not necessarily be attributable to regional base-level changes alone.
Evaluation for systematic purposes of the tarsometatarsal characters in Spheniscidae. The importance of the tarsometatarsus in the systematic studies of birds, and particularly of penguins, is well established. To determine the diagnostic value of metric characters of the tarsometatarsus, a multivari-ate analysis was performed using 8 variables measured in 46 adults specimens. The results allowed to dis-tinguish the different morphological patterns in the living and fossil Patagonian penguins, making possible to discriminate which variables are systematically significant. Resumen. – La importancia del tarsometatarso en los estudios sistemáticos de las aves, y en particular de los pingüinos, resulta indiscutible. A fines de determinar el valor diagnóstico de los caracteres métricos del tarsometatarso, se realizaron análisis multivariados utilizando 8 variables medidas en 46 especímenes adul-tos. Los resultados obtenidos permiten distinguir los diferentes patrones anatómicos de los pingüinos actuales y fósiles patagónicos que hacen posible discernir qué variables son sistemáticamente significativas. Aceptado el 8 de Febrero de 2007.
Introducción Todas las especies de pingüinos (Aves, Sphe-niscidae) son aves marinas no voladoras, que habitan los mares del Hemisferio Sur. Sus representantes más antiguos se conocen en el registro paleontológi-co desde el Paleoceno (Tambussi et al., 2005; Slack et al., 2006), hace unos 60,5-61,6 Ma. El singular patrón osteológico, común a todas sus especies, se encuentra estrechamente relacionado al hábito buceador que ha sido observado en todas las especies modernas y que presumiblemente sería también característico de los fósiles. En particular, los taxones miocenos registrados en América del Sur presentan un diseño esqueletario muy similar al de las formas actuales y muy diferente al de los grandes pingüinos que habitaban los mares australes duran-te el Eoceno de Antártida, Patagonia, Australia y Nueva Zelanda, y que se registran hasta el Oligoceno en los sedimentos marinos de estas tres últimas áre-as (Fordyce y Jones, 1990). El registro paleontológico de Argentina se encuen-tra conformado por importantes acumulaciones óse-as que aparecen en distintas áreas de la Patagonia. En su mayor parte, los restos corresponden a ele-mentos apendiculares y raramente se registran crá-neos o esqueletos completos (Acosta Hospitaleche, 2003, 2005). El inusual hallazgo de un esqueleto arti-culado recuperado en sedimentos de la Formación Gaiman ha brindado nuevas evidencias que permi-ten la asignación de Chubutodyptes biloculata Simp-son, 1970 al género Palaeospheniscus Moreno y Mer-cerat, 1891. El MEF-PV 1729, el único resto conocido proce-dente de la Formación Gaiman en la localidad de Puerto Madryn, fue hallado con sus elementos arti-culados (figura 1). La ausencia de marcas y fracturas permite pensar que no ha sido atacado por depreda-dores ni organismos carroñeros. Teniendo en cuenta estas evidencias, conjuntamente con los datos apor-tados por los estudios geológicos previos (Cortés, 1981), es posible inferir que el ambiente de deposita-ción habría sido de aguas someras pero relativamen-te tranquilas, lo cual habría posibilitado la buena preservación de este material, seguramente situado en una zona por debajo de la línea de olas. Se ha de-terminado además, que durante la formación de es-tos depósitos, la costa habría estado situada a unos AMEGHINIANA (Rev. Asoc. Paleontol. Argent.
The partial articulated skeleton MLP 77-V-10-1 comes from the upper levels of La Meseta Formation (Seymour Island, Antarctica) at the southwestern slope of the plateau. These remains were found in the Submeseta Allomember, within the Anthropornis nordenskjoeldi Biozone, dated at 34.2 Ma using strontium isotope ratios from shells. MLP 77-V-10-1 is a giant penguin, probably the largest ever described, whose coracoids are strikingly wide at the distal surface. The present contribution is a study of this new fossil penguin, with particular emphasis on the coracoids. The osteography and associated muscles are described. Functional connotations of coracoid morphology are thoroughly discussed and its implications on the mechanics of diving are explored. We concluded that the coracoid morphology suggests a change in diving strategy from the earliest penguins until the living representatives. In the oldest penguins, the improvement of diving capacity would have been linked to the development of stronger bone and probably muscular structures enabling endurance of greater forces operating in a denser medium. In contrast, the Neogene penguins would have optimized the force action of the flight apparatus by developing more precise movements, adjusting the angle of attack of each of the effective forces.
ABSTRACT: The penguin skeleton studied here constitutes the fourth partial skeleton found in Patagonia, and the third one with an associated humerus and tarsometatarsus. The finding of this partial skeleton identified with certainty as Palaeospheniscus patagonicus Moreno and Mercerat, 1891 (Aves, Sphenisciformes) allows the first description of elements other than the tarsometatarsus. The material comes from the basal sector of the Gaiman Formation (Early Miocene), located along the Atlantic coast of Chubut Province, south of awson city. This unit comprises a succession of shales, fine tuffs, sandstones, tuffaceous sandstones, and coquinas deposited in a shallow marine environment. These beds contain abundant marine vertebrates (sharks, dolphins, rays, birds), mollusk casts, and oyster beds. The skeleton includes: rostrum, two thoracic vertebrae, right coracoid without the distal end, left humerus, right femur, right tarsometatarsus, left fragmentary scapula, left coracoid, left radius without the distal end, proximal portion of left ulna, proximal end of left femur, and preacetabular part of the synsacrum. P. patagonicus would have been a medium-sized penguin weighing about 5 kg that inhabited the breeding colonies established in the nearby Bryn Gwyn area during the early Miocene. Despite the abundance of penguin remains known for Argentina, and the fact that they are among the birds with a better fossil record, this skeleton is an exceptional case. This finding allows a readjustment of the taxonomic criteria applicable to fossil and living species.
Some time ago, my friend Mr. Walter Mantell submitted to my examination two fossil bones from tertiary deposits at Kakaunui and Parimoa in New Zealand.
Of these, the one is the right tarso-metatarsal bone of a Bird belonging to the Penguin family, the other the humerus of a Cetacean of small size.
Fossil Bird.—The former bone (of which a front view is represented in fig. 1, and a back view in fig. 2) measures two inches and a half in extreme length, and rather more than an inch and a quarter across its proximal end. The precise width at the distal end cannot be given, as the innermot part of this extremity ofthe bone has been broken away; what remains measures inch.
The proximal end of the bone presents two articular facets,—the one internal, an oval, shallow concavity, looking upwards and a little inwards, the other, external, quadrilateral, slightly convex from before backwards, slightly concave from side to side, and inclined more obliquely upwards and outwards. The two facets are separated by a stout median ridge, which rises into a conical tuberosity anteriorly, but dies away posteriorly into a shallow triangular pit. The posterior edges of both facets are rather more raised than the anterior ones; and marked transverse depressions separate both from the upper extremities of the four strong calcaneal ridges which project from the upper part of the posterior face of the bone (fig. 2).
Of these, the innermost is the strongest and longest; and a deep groove divides it from the two middle ones,
Eocene Antarctic penguins, at least 10 species in six genera, are known only from the La Meseta Formation, Seymour Island, Antarctic Peninsula. They are most numerous (in terms of individuals, body sizes and taxa) in Late Eocene strata. Specimens from three species and phylogenetic analysis presented in this work shed new light on the systematics and evolution of Antarctic Sphenisciformes. The earliest reported bones of giant penguins from the genus Anthropornis set the conservative estimate of its divergence time at c . 53 Ma (Early Eocene). They also document the oldest known appearance of quite a high diversity of Sphenisciformes; altogether, three morphotypes (differing in size) have been found within the same sampling locality. A newly described, relatively small and intriguingly elongated, tarsometatarsus from the Late Eocene of the La Meseta Formation, belonging to another genus of large-sized Antarctic penguins ( Palaeeudyptes ), suggests the possible existence of an unnamed species within this long-established genus. The phylogenetic analysis based on tarsometatarsal features shows that the relationship between ‘ Archaeospheniscus ’ wimani and three species of Delphinornis (all of them co-existed during the Late Eocene time period) does not appear to be close enough to justify merging them into a single genus (as was recently postulated).
Supplementary material
An annotated data matrix used for the phylogenetic analysis is available at www.geolsoc.org.uk/SUP18599
The new genus and species Llanocetus denticrenatus is described based on a cranial endocast and portion of a dentary fragment bearing two teeth from the Eocene La Meseta Formation, Seymour Island, Antarctic Penninsula. Llanocetus new genus is designated the type genus for the new family Llanocetidae. The Llanocetidae is placed within the new infraorder Crenaticeti, co-ordinate with the new Mysticete infraorder Chaeomysticeti. Llanocetus denticrenatus new species shows relationship with both Archaeoceti and Mysticeti. Revision of archaeocete and mysticete classification includes proposal of the new taxa Kekenodontinae, Mammalodontidae, and the new ranks Protocetoidea, Remingtonocetoidea, Basilosauroidea, and Eschrichtioidea. The endocast shows evidence of intracranial retial hypertrophy, taken as evidence of enhanced diving abilities. The large deeply notched teeth are widely spaced on the lower jaw. I hypothesize that filter feeding in whales arose first in species in which teeth with deep notches, forming widey spaced tubercles, comprised part of a straining apparatus analogous to the serrated teeth of the phocid seal Lobodon carcinophagus.
The first installment of a catalogue of the fossil birds of the world covers 49 families in 15 orders of birds, or nearly half of the orders and about one-fourth of the families known. The species treated number 374, of which 273 are extinct, and 101 represent living species recorded from fossil or prehistoric sites. For the paleospecies the data include citation of the original description, synonyms, nature and repository of types, reference to pertinent revisionary papers, and detailed geological and geographic ranges, with bibliographic reference to their occurrence. Major taxonomic changes include recognition of three subclasses, Sauriurae for Archaeopteryx, Odontholcae for the Hesperornithidae, and Ornithurae for the remaining birds. Three infraclasses of Ornithurae are recognized, Dromaeognathae (for the Tinamidae), Ratitae, and Carinatae. Changes in position include transfer of the family Opisthodactylidae to the Rheiformes, Enaliornithidae to the Gaviiformes, and Baptornithidae to the Podicipediformes. On priority the ordinal name Ciconiiformes yields to Ardeiformes. Prior family names adopted include Emeidae for Anomalopterygidae, Oceanitidas for Hydrobatidae, and Plataleidae for Threskiornithidae. New taxa proposed are Colymboidinae (new subfamily, Gavildae), Cayetanornis (new genus, Tinamidae), and Palaeeudyptes marplesi (new species, Spheniscidae). The misprinted name Pelagodornithidae is emended to Plegadornithidae, to conform with the spelling of the type-genus.
Over the last decade, geometric morphometric methods have been applied increasingly to the study of human form. When too few landmarks are available, outlines can be digitized as series of discrete points. The individual points must be slid along a tangential direction so as to remove tangential variation, because contours should be homologous from subject to subject whereas their individual points need not. This variation can be removed by minimizing either bending energy (BE) or Procrustes distance (D) with respect to a mean reference form. Because these two criteria make different assumptions, it becomes necessary to study how these differences modify the results obtained. We performed bootstrapped-based Goodall's F-test, Foote's measurement, principal component (PC) and discriminant function analyses on human molars and craniometric data to compare the results obtained by the two criteria. Results show that: (1) F-scores and P-values were similar for both criteria; (2) results of Foote's measurement show that both criteria yield different estimates of within- and between-sample variation; (3) there is low correlation between the first PC axes obtained by D and BE; (4) the percentage of correct classification is similar for BE and D, but the ordination of groups along discriminant scores differs between them. The differences between criteria can alter the results when morphological variation in the sample is small, as in the analysis of modern human populations.
A new cetacean from the Late Eocene La Meseta Formation
- E D Mitchell
Mitchell, E.D., 1989. A new cetacean from the Late Eocene La Meseta Formation,
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The oldest record of the extant penguin genus Spheniscus
- U Gö Hlich
Gö hlich, U., 2007. The oldest record of the extant penguin genus Spheniscus, a
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TpsRelwVersion 1.49 and TpsUtil Version 1.56
- J Rohlf
Rohlf, J., 2013. TpsRelwVersion 1.49 and TpsUtil Version 1.56. Ecology & Evolution,
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Insty- 518 tut Biologii
- Uniwersytetu Warszawskiego
- Białymstoku
Uniwersytetu Warszawskiego w Białymstoku (PhD thesis, unpublished). Insty-
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tut Biologii, Uniwersytet Warszawski, Białystok.