Giants of the Pampean plains (Argentina) during Early Pleistocene (Ensenadan). The case of Panochthus (Xenarthra, Glyptodontidae): comparative descriptions
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... This genus is composed of only four species during the Pleistocene (Zurita et al., 2011b). The opposite is shown when dealing with the diversity of Panochthus, where a taxonomic expansion is observed during the Late Pleistocene with currently eight species included in the genus (Zamorano et al., 2021). Concerning the Doedicurinae, only one Pleistocene species, Doedicurus clavicaudatus Gervais & Ameghino, 1880, is well-established, but several authors proposed an intense taxonomic revision of this clade (e.g., Núñez-Blasco et al., 2021;Zurita et al., 2016). ...
... Dental homology for glyptodonts is unresolved and we follow conventional nomenclature considering the entire set of teeth as molariforms (e.g., González Ruiz et al., 2015). For external cranial anatomy and in addition of many description for glyptodont genera or subfamilies (e.g., Cuadrelli et al., 2020;Núñez-Blasco et al., 2021;Zamorano et al., 2021;Zurita et al., 2011b), we followed mainly Wible and Gaudin (2004) on Euphractus sexcinctus Linnaeus, 1758, complemented with the detailed anatomical description of the pampathere Holmesina floridanus Robertson, 1976(Gaudin & Lyon, 2017, a representative of the glyptodont's sistergroup (Billet et al., 2011;Gaudin & Wible, 2006). For anatomical nomenclature associated with the 3D braincase endocast, we cross-referenced different nomenclatures (Butler & Hodos, 1996;Dechaseaux, 1958Dechaseaux, , 1962Dozo, 1998;Gervais, 1869). ...
... Two radiations within the glyptodont have been identified (e.g., Nuñez-Blasco et al., 2021). One corresponds to the Hoplophorinae, a clade notably formed by the grouping of Panochthus and Neosclerocalyptus, two genera including eight species and four species during this period, respectively (Zamorano et al., 2021;Zurita et al., 2011b). The second correspond to the Glyptodontinae, which, during the Pleistocene, consisted only of the genus Glyptodon, restricted to South America, and the genus Glyptotherium Osborn, 1903, more widely distributed in North America and in northern South America . ...
With their odd cranial features, glyptodonts, closely related to extant armadillos, are a highly diverse group of the South American megafauna. Doedicurus, Glyptodon, Panochthus, and Neosclerocalyptus were present in the “Pampean Formation” during the Pleistocene, and they are all exceptionally preserved in the Santiago Roth Collection, thus ofering the possibility of investigating these four well-diversifed genera. A total of 13 specimens (seven species) were analysed and compared in a qualitative/quantitative study of external cranial remains and endocranial reconstructions (i.e., braincase and associated cranial canals, and inner ears). We report on anatomical features that contribute to existing phylogenetic matrices; many of them are new potential synapomorphies supporting the current hypotheses regarding the evolutionary history of the Pleistocene glyptodonts. These include the anterior cranial shape, the position of the basicranium in respect to the whole cranium, the shape of the cranial roof, the position of the largest semicircular canal, and the inclination of the cerebrum. They may represent new shared-derived features among Glyptodon, Doedicurus, Neosclerocalyptus, and Panochthus. We also provide detailed comparative descriptions highlighting new potential convergences in respect to current phylogenies, concerning, for instance, the shape of the foramen magnum, the global shape of the cranium, orbital shape, cochlear position, and a strong protrusion of the zygomatic process of the squamosal. In light of these results, we discuss morphological transformations across phylogeny. The endocranial comparison brought insights on the phylogenetic patterns of cranial canal evolution.
... Glyptodon tuberculatus Owen 1845. Pleistoceno Medio-Holoceno Temprano de Argentina, Bolivia, Paraguay, Brasil y Uruguay (Hoffstetter, 1978;Marshall y Sempere, 1991;Cione y Tonni, 1999;Ubilla et al., 2009;Ferrero et al., 2017;Zamorano et al., 2021). (Owen, 1845) Descripción. ...
... Panochthus tuberculatus es la única especie reconocida para el Pleistoceno Tardío-Holoceno Temprano de Argentina, Uruguay, centro y sur de Bolivia y sur de Brasil (Zamorano et al., 2021). Junto con G. reticulatus son los gliptodontes con registros más frecuentes en el Pleistoceno Tardío de Sudamérica. ...
... En Entre Ríos proviene fundamentalmente de la FSAE asociada al MIS 5 (Ferrero et al., 2017), y no como indica Cuadrelli et al. (2019) que proceden de la Formación Tezanos Pinto. Es evidente que fueron exitosos para ocupar una gran diversidad de ambientes con climas fríos a cálidos de características tropicales y subtropicales tanto de llanuras como de altura (Zamorano et al., 2021). Hasta el momento, los registros del taxón eran fragmentarios en Entre Ríos y fundamentalmente correspondían a porciones de corazas o placas aisladas (Ferrero, 2009). ...
En esta contribución se dan a conocer nuevos registros de mamíferos del Pleistoceno Tardío de la Provincia de Entre Ríos. Los fósiles provienen de la Formación Salto Ander Egg, una unidad depositada en los valles fluviales del sudoeste entrerriano con una edad, obtenida por OSL, entre los 120 ka y los 60 ka. Se interpreta que las secuencias de la formación fueron acumuladas durante el MIS 5. El contenido paleontológico de la unidad constituye el registro que mejor caracteriza el inicio del Pleistoceno Tardío para América del Sur y la transición MIS 5e-MIS 5c. En este trabajo se describen 12 taxones: cf. Ozotoceros bezoarticus (Cervidae), Morenelaphus cf. brachyceros (Cervidae), Hemiauchenia paradoxa (Camelidae), Lama guanicoe (Camelidae), Mylodon darwini (Mylodontidae), Glossotherium robustum (Mylodontidae), Lestodon armatus (Mylodontidae), Glyptodon reticulatus (Glyptodontidae), Panochthus tuberculatus (Glyptodontidae), Eutatus seguini (Dasypodidae), Notiomastodon platensis (Gomphotheriidae) y Toxodon platensis (Toxodontidae). La mayoría de ellos son nuevos registros y constituyen ejemplares más completos que los previamente conocidos para la unidad. Mylodon darwini es el primer registro en la Formación Salto Ander Egg y extiende ampliamente su distribución geográfica en la provincia. Además, se da a conocer una nueva localidad fosilífera correspondiente al Arroyo El Bellaco (Departamento Diamante) y se incrementa notablemente el número de registros para el sitio Arroyo El Pelado que hasta el momento se conocía por solo tres hallazgos.
... A recent study produced the comparative description of Panochthus species from the Pampean Region from the Ensenadan (Zamorano et al., 2021). The authors support the presence of just three species of Panochthus in this region at this period: Pan. ...
... subintermedius (Zamorano, 2012). While the shape and size of the fingers and toes of PIMUZ A/V 433 are consistent with assignment to the genus (see Schulthess, 1920), the main argument for the determination is supported by the ornamentation of the multiple osteoderms corresponding to numerous polygonal tubercles equal in size on a single osteoderm (Zamorano et al., 2014a(Zamorano et al., , 2021. This feature is unique to certain regions of the dorsal carapace of Pan. ...
... intermedius and only the last row of the posterior margin of the carapace for Pan. subintermedius (Zamorano et al., 2021). In PIMUZ A/V 433 and PIMUZ A/V 435, many osteoderms show no central figure, which indicates other regions of the dorsal carapace with more hexagonal shapes for the more dorsal part, and more quadrangular shapes for the more lateral part (Zamorano et al., 2021). ...
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The present work concerns xenarthrans from the collection of Santiago (Kaspar Jakob) Roth (1850-1924) housed at the Palaeontological Institute and Museum of the University of Zurich, one of the most important collections of Pleistocene mammals from Argentina in Europe. Roth was a paleontologist originally from Switzerland who prospected and collected a large amount of Pleistocene megafauna of the Pampean Region of Argentina. The xenarthrans are the main representatives of this collection in Zurich, with 150 specimens. Since 1920, this material has not been revised and is under studied. The present investigation corresponds to a taxonomic revision resulting in 114 reassignments, leading to document xenarthran diversity and discuss their paleoecologies. The high diversity reflects the paleoecology of the Pampean Region during the Pleistocene, with the various abiotic events that impacted the paleoenvironment of this region. Within the Cingulata, the Pampean Region fauna was probably dominated by glyptodonts with a high representation of Glyptodontinae and Neosclerocalyptinae while within the sloths the highest diversity and abundance is found in the Mylodontinae and Scelidotheriinae. These four clades represent both species with high ecological tolerance (e.g., Glyptodon munizi; Catonyx tarijensis) and ecologically highly specialized species (e.g., Neosclerocalyptus paskoensis; Scelidotherium leptocephalum). The presence of such ecological diversity underlines the status of the Pampean Region as a major interest for paleoecological and paleoenvironmental reconstruction.
Supplementary information:
The online version contains supplementary material available at 10.1186/s13358-023-00265-7.
... Another interesting point concerns the linear measurements and body mass achieved by glyptodonts. An evident increase of this key biological variable is observed in these large armoured herbivores in different moments of their evolutionary history, such as the Oligocene (see Scillato-Yan e, 1977) and Pleistocene (Soibelzon et al., 2012;Tambusso & Fariña, 2015;Zamorano et al., 2021;Zurita et al., 2010), when some glyptodonts (e.g. D. clavicaudatus, Panochthus cf. ...
... This is particularly evident in those taxa that inhabited high-altitude ecosystems in the Eastern Cordillera of Bolivia, associated with high primary productivity and high biodiversity (Wardle, 1991;Roger and Walker, 2005;Burke 2007;Sadler and Bradfield, 2010;Sánchez-Saldías and Fariña, 2014) such as P. hipsilis and UATF-V n/n, or those species from the Amazon, related to dense vegetation and high humidity levels, such as P. jaguaribensis (Scillato-Yané et al., 1995;Vivo and Camingnotto, 2004;Cione et al., 2009;Zamorano et al., 2014). Both cases contrasting with the Pampean species, commonly associated with temperate savannas and temperate grasslands related to high variation of annual temperature (Ray and Adams, 2001;Vivo and Carmignotto, 2004;Mayle, 2006;Varela et al., 2018), such as P. frenzelianus, P. subintermedius and P. florensis (Zurita et al., 2017;Zamorano et al., 2021). ...
Panochthus Burmeister is one of the most diversified and widely distributed glyptodonts in the Pleistocene of South America, which includes areas located at high altitudes (>4,000 m.a.s.l.). Within the genus, eight species (P. intermedius Lydekker, P. subintermedius Castellanos, P. tuberculatus (Owen), P. frenzelianus Ameghino, P. greslebini Castellanos, P. jaguaribensis Moreira, P. hipsilis Zurita, Zamorano, Scillato-Yané, Fidel, Iriondo and Gillette, and P. florensis Brambilla, Lopez and Parent) are currently recognized. Here, we report a dorsal carapace (UATF-V n/n) from the Pleistocene of the surroundings of Potosi, Bolivia, that shows some morphological particularities when compared to the carapace of P. intermedius, P. frenzelianus, P. subintermediusand P. tuberculatus, including: a) its maximum dorso-ventral diameter is at the anterior half, meanwhile in other species is at mid-point (e.g., Propalaehoplophorus) or at posterior half (e.g., Glyptodon); b) the dorsal profile is different in comparison to other glyptodonts (e.g., Glyptodon, Glyptotherium, Neosclerocalyptus, Propalaehoplophorus); c) the ornamentation pattern of the osteoderms shows a central figure surrounded by small polygonal figures along the most exposed surface of the carapace (except for the mid-dorsal region that shows reticular ornamentation pattern), being different from that of the remaining species, in which central figures are limited to the caudal/cephalic and most lateral regions of the carapace. In summary, the combination of characters suggests that it could belong to a new species or, alternatively, to P. floriensis or P. jaguaribensis in which the dorsal carapace is not yet known. The phylogenetic analysis confirms its basal position among Panochthus and highlights the importance of these high elevation areas of the Andes in South America in order to understand the complex evolutionary history of glyptodonts.
... Among the latter, glyptodonts, fully armoured mammals closely related to armadillos, are one of the most interesting groups of the South American fossil faunas, with over 65 genera described (McKenna and Bell 1997), spanning from the Late Eocene until their demise at the Early Holocene (Fariña et al. 2013;Zurita et al. 2016). They varied from sheep-sized forms to the large (although poorly known) Deseadan species and the very giants of the Pleistocene (Fariña et al. 1998;Zamorano et al. 2021), with their adult body masses estimated as exceeding one tonne. Many aspects of their palaeobiology have deserved attention in the last decades, as the peculiar morphology and biomechanics of their masticatory apparatus (Fariña and Parietti 1983;Fariña 1985Fariña , 1988Fariña and Vizcaíno 2001), as well as their posture, locomotion and agonistic behaviour (Alexander et al. 1999;Fariña 1996;Blanco et al. 2009). ...
With eight species, Panochthus is one of the most abundant and diverse glyptodont genera during the Pleistocene of South America, as well as one of the largest glyptodonts. The relationship between the shape of the tube and its usage as weapons in the species of Panochthus is explored here; moreover, we intend to assess how they evolved among the species of the genus Panochthus. The morphology of the caudal tube is: (1) ≈conical-cylindrical and (2) hilt-less Viking style sword. The form (1) is represented in P. subintermedius from Early Pleistocene – Middle Pleistocene (Ensenadan). The form (2) is present in the specimens from the Middle – Late Pleistocene (Bonaerian-Lujanian): P. tuberculatus, P. greslebini, P. florensis. P. intermedius, P. frenzelianus, P. jaguaribensis and P. hipsilis is not considered. The shape of the caudal tube (1) allows the glyptodont to perform its blows more effectively in all directions; which implies hitting with less precision. Whereas, the form (2) style of Viking sword, has the greater effectiveness in the blows delivered in a horizontal movement that requires greater accuracy. In the more recent species of Panochthus, those that show the form (2) present also more ornamentations that were possibly covered by corneous structures.
On the phylogenetic position of a particular specimen of Panochthus (Xenarthra, Glyptodontidae): an analysis based exclusively on characteristics of the dorsal carapace. The monophyly of Xenarthra is supported by morphological and molecular characters, ancient DNA and collagen. Phylogenetic work also supports the idea of a common ancestor for the Cingulata; Glyptodontidae is considered a natural group too; this also occurs with the genus Panochthus, which includes eight species. The phylogenetic relationships of a peculiar specimen UATF-V s/n, assigned to Panochthus sp. were examined through a cladistic analysis carried out exclusively with characters from the dorsal carapace. A maximum parsimony tree with L = 49, CI = 0.84 and IR = 0.74 was obtained through the analysis of a matrix of 14 taxa and 29 characters. The cladogram comprises two large groups: node A includes Nopachtus coagmentatus, N. cabrerai, Propanochthus bullifer, Phlyctaenopyga ameghini; and node B contains Glyptodon reticulatus, Hoplophorus euphractus, Neosclerocalyptus ornatus, Panochthus intermedius, P. subintermedius, P. tuberculatus, P. greslebini, P. hipsilis and UATF-V s/n. The specimen UATF-V s/n is positioned as the sister taxon of all Panochthus spp., having most plesiomorphic characters than other species of the genus. Glyptodon reticulatus appears as the sister group of Panochthus, presenting osteoderms of the mid-dorsal region with a reticular pattern. The characteristic of these osteoderms without a central figure is shared with G. reticulatus and Neuryurus trabeculatus; this feature is interpreted as an evolutionary convergence. The exclusive feature of Panochthus is that the mid-dorsal region and the anterior part of the mid-lateral region of the dorsal carapace are formed by ornate osteoderms following a reticular pattern. Keywords: Glyptodontidae, Panochthus, phylogeny, dorsal carapace, osteoderms, reticular pattern.
A partir de la última década del siglo XX, siguiendo la tendencia mundial al desarrollo de esquemas cronológicos con base bioestratigráfica, comenzaron las contribuciones de Eduardo Pedro Tonni, Alberto Luis Cione y Colaboradores sobre esta temática en Argentina. Ellos propusieron para el sector oriental de la región pampeana de Argentina, una secuencia bioestratigráfica casi continua desde el Mioceno Tardío hasta el Holoceno. La misma conforma actualmente la base de la escala cronológica para el Cenozoico tardío continental de América del Sur. El refinamiento de la secuencia bioestratigráfica pampeana permitió: 1-establecer la cronología para el arribo de los mamíferos de origen holártico al extremo más austral de América del Sur durante el Gran Intercambio Biótico Americano; 2-precisar la dinámica faunística e interpretar los cambios paleobiogeográficos vinculados a las fluctuaciones climáticas del Cenozoico tardío; y 3-establecer correlaciones entre las secciones tipo de la región pampeana con áreas extra-pampeanas, incluso de otros países del continente. Resulta indiscutible la labor desarrollada durante más de 30 años de trabajo liderado por Tonni y Cione en colaboración con otros especialistas, para rever el concepto de “Edades Mamífero” y retornar a la clasificación cronoestratigráfica-geocronológica con base bioestratigráfica. En este contexto, aquí realizamosuna actualización y síntesis del esquema bioestratigráfico, de su composición mastofaunística y de los principales cambios climáticos ocurridos durante el Cuaternario en la región pampeana, junto a una breve sinopsis de la carrera de E. P. Tonni y su aporte a la paleontología de vertebrados.
Panochthus Burmeister constituye uno de los xenartros más abundantes, diversificados y ampliamente distribuidos del Pleistoceno sudamericano, como así también uno de los gliptodóntidos de mayor distribución latitudinal y altitudinal. En esta contribución se analizan aquellos registros asignables al género, efectuados en áreas de altura, en orden decreciente de altitud: (1) MURB 1906: ̴ 4000 m.s.n.m, Potosí (Bolivia); (2) MUSM 3632: ̴ 3800 m.s.n.m, Desaguadero (Perú); (3) MHNC-13491: ̴ 2600 m.s.n.m, Cochabamba (Bolivia); (4) MNPA-V 006598: ̴ 1870 m.s.n.m, Valle de Tarija (Bolivia); (5) MUFYCA 383: ̴ 920 m.s.n.m, Valle de Traslasierra (Argentina). Se discute la probable relación existente entre la altitud geográfica y la masa corporal de los ejemplares de P. intermedius Lydekker. En esta especie se observa que los individuos que habitan áreas de altura muestran valores de masa corporal significativamente menores que los de aquellos de la llanura pampeana. Esta relación también se registra en otros xenartros, así como en otros grupos de mamíferos. Estos taxones expresarían un patrón inverso de la regla de Bergmann. De esta manera, la “reducción de la disponibilidad de recursos” podría ser la razón ecológica que explicaría el menor tamaño de los individuos estudiados. Finalmente, P. hipsilis Zurita, Zamorano, Scillato-Yané, Fidel, Iriondo & Gillette es una especie endémica del Altiplano Boliviano y sus restos son los hallazgos de Panochthus y, posiblemente, de Glyptodontidae realizados a mayores alturas.
Burmeister reconoció la especie Panochthus bullifer basándose en restos procedentes de sedimentos neógenos de las sierras de Córdoba. El material tipo de esta especie procede del “Brocherense” de Castellanos. En esta contribución se presenta por primera vez la diagnosis formal de Propanochthus bullifer. Asimismo, se describe el material empleando una terminología más actualizada y apropiada, comparándolo con el de especies afines. El holotipo corresponde a un fragmento de la región posterodorsal de la coraza dorsal y al tubo caudal completo. La ornamentación de los osteodermos de la coraza tiene una gran figura central rodeada por varias hileras (hasta cinco) de figuritas periféricas. La figura central de la zona más anterior es plana y la de la zona posterior convexa, en algunos casos bastante abultada. En los osteodermos del margen posterior, la figura central se ubica caudalmente y está precedida por hasta siete hileras de figuritas. El tubo caudal es más grácil que en Panochthus; es deprimido y su extremo distal es notoriamente romo. Dorsalmente su ornamentación está constituida por figuras centrales planas rodeadas de una hilera de figuritas periféricas (excepcionalmente dos); lateralmente, posee cuatro grandes figuras subelípticas rugosas rodeadas por figuritas y separadas entre sí por dos figuras enfrentadas, menores, subelípticas y rugosas. A su vez, se señala la distribución estratigráfica y geográfica, Formación Brochero (Montehermosense-Chapadmalalense [Plioceno temprano-Plioceno tardío]) de las Sierras de Córdoba; también se discute y se aclara la cronológica
En el actual territorio de la provincia de Buenos Aires se encuentran secuencias sedimentarias con abundante contenido fósil, que constituyen la base de la escala cronológica sudamericana para el Neógeno y Cuaternario. Desde la segunda mitad del siglo XIX y especialmente a partir del aporte de Florentino Ameghino, comenzó a desarrollarse un esquema estratigráfico con base en el contenido paleontológico.
Los sedimentos portadores fueron denominados de diferentes maneras: “pampean formation”, “limo pampa”, “terreno pampa”, o “formación pampeana”, entre otras. Es Ameghino quien divide y denomina “pisos” u “horizontes” pampeanos (ej. “piso pampeano lacustre o lujanense”, “piso pampeano medio o belgranense”). Estos nombres posteriormente se utilizaron como base de las secuencias de “Edades Mamífero” y, más recientemente y de acuerdo al Código Argentino de Estratigrafía, para designar Pisos/Edades. Así, el Pleistoceno incluye el Subpiso Sanandresense (del Piso Marplatense) y los Pisos Ensenadense, Bonaerense y Lujanense, portadores de una mastofauna que caracteriza y define a las biozonas que los sustentan (Ctenomys chapalmalensis, Mesotherium cristatum, Megatherium americanum, Equus (Amerhippus) neogaeus). A través de este esquema, se pueden establecer adecuadas relaciones de superposición, de primeros y últimos registros, así como de abundancia de fósiles y establecer cronologías acertadas para procesos tales como el Gran Intercambio Biótico Americano. Asimismo, se registran numerosos eventos glaciales e interglaciales que provocaron desplazamientos de la fauna. Varios de los perfiles tipo o localidades clásicas estudiadas durante más de 150 años han desaparecido (como “toscas del Río de La Plata”, Punta Hermengo o el puerto de La Plata en Ensenada) en virtud de la actividad humana.
Resumen-Panochthus Burmeister es uno de los géneros de gliptodóntidos más amplia-mente distribuidos geográficamente en el Pleistoceno del sur de América del Sur. Revisiones sistemáticas recientes revelaron la existencia de siete especies: P. intermedius Lydekker, P. subintermedius Castellanos, P. tuberculatus (Owen), P. frenzelianus Ameghino, P. greslebini Castellanos, P. jaguaribensis Moreira y P. hipsilis Zurita, Zamorano, Scillato-Yané, Fidel, Iriondo y Gillette. En esta contribución se describe un osteodermo que proviene del Pleistoceno de la ribera del río Desaguadero, Perú, aproximadamente a 3800 metros sobre el nivel del mar. La presencia, en su superficie externa, de figuras reducidas que siguen un patrón reticular permite atribuirlo a Panochthus. Este es el primer registro de este género en Perúy , de esta manera, se amplía su distribución geográfica conocida. Palabras clave: Glyptodontidae, Panochthus, Pleistoceno, paleogeografía, Perú. ä Abstract-Panochthus Burmeister is one of the most geographically widespread glypto-dontid genera in the Pleistocene of southern South America. Recent systematic revisions revealed the presence of seven species: P. intermedius Lydekker, P. subintermedius Castellanos, P. tuberculatus (Owen), P. frenzelianus Ameghino, P. greslebini Castellanos, P. jaguaribensis Moreira and P. hipsilis Zurita, Zamorano, Scillato-Yané, Fidel, Iriondo and Gillette. An osteo-derm from Pleistocene deposits cropping out on the banks of the Desaguadero River, Peru, at about 3800 meters above sea level, is described herein. The presence of a clear reticular pattern on the outer surface of the osteoderm is indicative of Panochthus. This is the first record of Panochthus from Peru and, thus, the geographic range of the genus is extended.
Phylogenetic relationships among 36 Recent and 42 extinct species of the Caninae (Canidae) were analysed, based on 360 morphological, developmental, ecological, behavioural and cytogenetic characters and 24 mitochondrial and nuclear markers. Primary phylogenetic analyses were accompanied by experimental analyses based on various combinations of data partitions and taxon samples. Leptocyon was recovered as a paraphyletic stem lineage of the Caninae; monophyly/paraphyly of the fox‐like canids (Vulpini) remains uncertain; Urocyon and Metalopex form a clade, possibly sister to all non‐Leptocyon canids; Otocyon, Nyctereutes and Nurocyon form a clade; dog‐like canids (Canini) are monophyletic (with South American Cerdocyonina and Afro‐Holarctic Canina); all South American hypercarnivores (Canis gezi, Protocyon, Speothos, Theriodictis) form a clade, close to Chrysocyon and Dusicyon; Canis arnensis, C. ferox, C. thooides, C. lepophagus and Eucyon spp. are basal to the Canina; Lycaon is an isolated African hypercarnivore; Cuon and its relatives (Xenocyon, possibly also Canis antonii, C. falconeri and Cynotherium) form a clade close to Canis s. str.; C. edwardii–C. etruscus–C. mosbachensis–C. palmidens–C. variabilis and hypercarnivorous Canis armbrusteri–C. dirus clades belong to Canis s. str. As the highly homoplastic morphological characters connected to dietary biology are the prominent characters available for the key fossil species, we conclude that macroevolutionary and palaeoecological analyses of the extinct and extant Caninae were to some extent compromised by the phylogenies used.
The main function of the hyoid apparatus in mammals is to control the entry and exit of air in the body, provide support to the tongue, hold it in position and give it movement. In some species, it also participates in the modulation of sounds produced by vocal cords. Its preservation as fossil is exceptional and very little known. It allows proposing hypotheses about how the mentioned functions would be carried out. The finding and study of two new specimens assigned to the glyptodontid Panochthus sp., from Lujanian sediments (late Pleistocene) of the Pampean region, permitted: 1-to study the anatomy and propose a new organization of the hyoid apparatus in glyptodontids, 2-to describe in detail its elements (even the thyroid cartilage), 3- to compare it with materials already published of Glyptodon cf. G. clavipes, and 4- to infer the musculature. In adult mammals, this apparatus is formed generally by 10 bony elements, (1) stylohyals (paired), (2) epihyals (paired), (3) ceratohyals (paired), (4) thyrohyals (paired) and (5) basihyal (unpaired); and 2 paired cartilaginous elements, (a) tympanohyals and (b) chondrohyals. In glyptodonts, the elements (1), (2), (3) form the sigmohyals (paired), and (4) and (5) the V-bone (unpaired). The bony elements of Panochthus sp. are more gracile and long than those of Glyptodon cf. G. clavipes, and in the former, the musculatura is more developed. The study of the new specimens suggests that Panochthus sp. could have more freedom of tongue movement than Glyptodon cf. G. clavipes, which possibly implied a different use of food resources.
Numerous climatic fluctuations occurred during the Cenozoic (last 66 Ma BP); some of them were drastic (e.g.,
during the Eocene-Oligocene boundary) while others were more gradual (e.g., late Tertiary cooling), but both have deep effect on the biotas. Armadillos are exclusively from the Americas; they have an old evolutionary history in South America and faunal replacement and/or local extinctions were detected, linked with climatic fluctuations. The global cooling of the late Eocene - early Oligocene coincides with a welldocumented faunal turnover of Dasypodinae by Euphractinae in Patagonia. During cold and arid periods of the Quaternary, Euphractinae and Tolypeutinae moved more than once to the eastern Pampean Region, and Dasypodinae moved northward to central Brazil or even further north to the Guyana Region. During interglacial periods some armadillos went extinct locally and/or moved to Patagonia (Zaedyus), central Argentina (Tolypeutes matacus, Chaetophractus vellerosus), or from the north to Mesopotamia and the Pampean Region (Dasypus). Since the end of the Pleistocene/early Holocene, human activity has strongly impacted armadillo populations. Currently,
the eastern Pampean Region (Argentina) is characterized by the presence of the couple C. villosus - D. hybridus (probably established since the late Holocene), but during the Pleistocene was Z. pichiy – T. matacus while Z. pichiy - C. villosus characterized early-middle Holocene. This work serves as evidence that paleozoological studies can be used to assess responses of biological systems to large scale perturbations and is the basis for studying future species distributions, in order to identify species in danger of extinction and establish management actions.
In the late Pleistocene, Panochthus was the most diverse genus of glyptodontids with five species: P. jaguaribensis, endemic to the intertropical region of Brazil, P. hipsilis from Bolivia, P. greslebini from Brazil and Argentina, P. tuberculatus from Uruguay and Argentina and P. frenzelianus, probably from the Pampean region, Argentina. In this paper we describe the robust caudal tube of a new species, Panochthus florensis n. sp., that inhabited the center of the Pampean region of Argentina at the end of the Pleistocene. The reduction in the number of central figures, a single apical figure, the absence of an apexian figure, and the lack of figures between the first pair of dorsal figures allow a rapid differentiation from the already known species. The striking diversity of Panochthus contrasting with that of other late Pleistocene glyptodontids, lead us to propose hypotheses for explaining this fact.