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Maximum likelihood molecular phylogeny of Hexactinellida, based on combined rRNA and COI genes (Dohrmann et al. 2012a). Clade support values are bootstrap proportions; scale bar indicates expected number of substitutions per site. Black dots indicate calibration nodes; ages in million years ago (Ma). See text for explanation and references. Note: the species Nodastrella asconemaoida corresponds to Rossella nodastrella in Dohrmann et al. (2012a); see Dohrman et al. (2012b).
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Reconciliation of paleontological and molecular phylogenetic evidence holds great promise
for a better understanding of the temporal succession of cladogenesis and character evolution,
especially for taxa with a fragmentary fossil record and uncertain classification. In zoology, studies of
this kind have largely been restricted to Bilateria. Hexact...
Citations
... This is not coincidental; many members of the family possess a diagnostic macroscopic character (a supradermal veil of projecting hypodermal pentactins) that is unique to that group, although the most recent studies (Botting et al., , 2020 indicate that this feature arose deep within the stem lineage of the family, since certain other features typical of the family were not (or only weakly) developed. However, the Rossellidae are considered on molecular phylogenetic grounds to be among the later of the modern families to have separated (Dohrmann et al., 2013(Dohrmann et al., , 2017, and recent discoveries from the Anji Biota (Botting et al., 2022) also confirm the presence of the crown group of Euplectellidae in the latest Ordovician. We should therefore anticipate that other families, perhaps more difficult to identify confidently as fossils, should have been present at this time. ...
Modern hexactinellid sponges are diverse, but almost exclusively deep-marine organisms with a very intermittent fossil record. Aside from the fused skeletons of hexactinosan lineages (which are also exceptionally rare in Palaeozoic sediments), identifying other families is challenging due to the microscopic nature of many diagnostic characters, and the need for exceptional preservation in a deep-water palaeoenvironment. Among the more distinctive living families is the Hyalonematidae, which have several preservable diagnostic features. A new sponge (Nectocollare zakdouli n. gen. n. sp.) from the Middle Ordovician Castle Bank fauna of Wales, UK, shows several of these characters, including pinular pentactine dermalia, unbundled choanosomal diactins, and a reticulate marginal rim at the apex. No root tuft is preserved, but these are often detached from fossil sponges. Although there remains some uncertainty over the assignment to Hyalonematidae, this sponge represents the only probable example from the Palaeozoic. Even in the absence of diagnostic microscleres, it likely represents a derived, crown-group hexactinellid, and further confirms the diversification of the class during the earliest Palaeozoic.
... One of the only marine sponges that unequivocally meet all criteria of a species flocks are glass sponges (genus Rossella), endemic to the Weddell Sea (Antarctica). The radiation in this genus, with at least 5 recognized species, is believed to be a product of Antarctic isolation events and the ecological opportunity thereby provided, as both the origin of Rossella (40 ± 20 Ma) and the opening of the Drake passage (~30 Ma, a key event in isolating Antarctica) share a similar timeline (Lawver and Gahagan 2003;Dohrmann et al. 2013). One of the 5 species, Rossella ricovitzae, is likely a species complex with 4 lineages defined by high morphological diversity and monophyletic mtDNA lineages (Vargas et al. 2017). ...
Species flocks are proliferations of closely-related species, usually after colonization of depauperate habitat. These radiations are abundant on oceanic islands and in ancient freshwater lakes, but rare in marine habitats. This contrast is well documented in the Hawaiian Archipelago, where terrestrial examples include the speciose silverswords (sunflower family Asteraceae), Drosophila fruit flies, and honeycreepers (passerine birds), all derived from one or a few ancestral lineages. The marine fauna of Hawai'i is also the product of rare colonization events, but these colonizations usually yield only one species. Dispersal ability is key to understanding this evolutionary inequity. While terrestrial fauna rarely colonize between oceanic islands, marine fauna with pelagic larvae can make this leap in every generation. An informative exception is the marine fauna that lack a pelagic larval stage. These low-dispersal species emulate a "terrestrial" mode of reproduction (brooding, viviparity, crawl-away larvae), yielding marine species flocks in scattered locations around the world. Elsewhere, aquatic species flocks are concentrated in specific geographic settings, including the ancient lakes of Baikal (Siberia) and Tanganyika (eastern Africa), and Antarctica. These locations host multiple species flocks across a broad taxonomic spectrum, indicating a unifying evolutionary phenomenon. Hence marine species flocks can be singular cases that arise due to restricted dispersal or other intrinsic features, or they can be geographically clustered, promoted by extrinsic ecological circumstances. Here, we review and contrast intrinsic cases of species flocks in individual taxa, and extrinsic cases of geological/ecological opportunity, to elucidate the processes of species radiations.
... The only articulated specimen from the Upper Cretaceous shows hypodermal pentactines protruding the surface of the sponge body as prostalia. Recent molecular phylogenetic investigation illustrates the divergence time of the Rossellidae from its sistergroup (Leucopsacidae) at 294.7 Ma, roughly coeval to the Carboniferous-Permian boundary, and the crown-group of Rossellidae first appeared at 218.2 Ma, corresponding to the Late Triassic (Dohrmann et al. 2013). Until earlier fossils were discovered, this molecular data seemed to be congruent with the fossil record of the rossellids. ...
Rossellids are geographically widespread in the modern deep-water sponge community. They are referred to Lyssacinosida, characterized by hypodermal pentactines and choanosomal megascleres of hexactines and diactines or the latter only. The fossil records of rossellids are usually found in the Cenozoic, with the earliest existence known from the Upper Cretaceous, later than the molecular phylogenetic result. A new lyssacinosan hexactinellid, Palaeorossella sinensis gen. et sp. nov., is described from the uppermost Ordovician of Anhui, South China. The sponge shows a saccular, globular or oval form with relatively thick wall. The skeleton is lyssacine type mainly composed of hexactines and stauractines, with the outer margin reinforced by hypodermal pentactines, which usually protrude the periphery as prostalia lateralia. The new species is well-preserved with typical hypodermal and prostalia pentactines as well as an articulated skeleton, giving some tentative insights into the affinity between the new species and other taxa in Rossellidae. It represents the oldest record of rossellids, providing new information for understanding the phylogeny of rossellids and on the evolution of modern Hexactinellida.
... Although there is no exact counterpart for the large projecting pentactins in Caulophacus, such hypodermal pentactine prostalia are indeed limited in modern faunas to the Rossellidae (Tabachnick 2002). Although the origins of the family are believed to be in the Late Palaeozoic based on molecular clock data (Dohrmann et al. 2013), a putative stem-group rossellid, Matteolaspongia hemiglobosa, also featuring pentactine prostalia, has now been described by the Late Ordovician of China . A rossellid affinity is, therefore, possible, despite the early date and unusual shallow-water environment. ...
The Pentland Hills sponge fauna (Llandovery, Telychian) consists of an unusual, aberrant assemblage, but of low diversity. A new specimen of a unique sponge, Eoghanospongia carlinslowpensis gen. et sp. nov., is described from the classic locality of R82. The mushroom-shaped, probably stalked body (peduncle attachment to body not exposed) resembles that of some living rossellids, especially Caulophacus . The sponge also shows prominent projecting pentactins and monaxon derivatives – a spicule type diagnostic of the Rossellidae among living taxa, albeit in a robust form not described from extant sponges, including Caulophacus or other pedunculate lyssacinosidans. Certain attribution to the Rossellidae is not possible from the single specimen, largely because of weak preservation of the primary spicule skeleton, but no other fossil or modern sponges show any significant similarity to it. Although similarly early relatives of the Rossellidae have recently been described from elsewhere, the new sponge is even more unexpected in being from a shallow-water environment, making the absence of rossellids through the rest of the Palaeozoic much more problematic.
... Usually, the monogamous spongicolid shrimps live within the atrium of their hosts from the larval stage, which has a beautiful and well-known name, called the Venus's Flower-basket (Euplectella) (Miers, 2008). The hosts of spongicolid shrimps are mainly from nine genus, and the origin of these hosts were placed in the late Mesozoic (78-144 Mya) (Goy, 2010;Dohrmann et al., 2013). Although only one representative of Spongicolidae was included in our analysis, the divergence time of spongicolid shrimp is in good agreement with the origin of their hosts. ...
Stenopodidea Claus, 1872 (Crustacea: Decapoda) is one of the major groups of decapods crustaceans. Hitherto, only one complete mitochondrial genome (mitogenome) from the family Stenopodidae is available for the infraorder Stenopodidea. Here, we determined the complete mitogenome of Spongiocaris panglao de Grave and Saito, 2016 using Illumina sequencing, representing the first species from the family Spongicolidae. The 15,909 bp genome is a circular molecule and consists of 13 protein-coding genes (PCGs), 2 ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes and one control region. Although the overall genome organization is typical for metazoans, the mitogenome of S. panglao shows some derived characters. A + T content of 77.42% in S. pamglao mitogenome is second-highest among the dacapods described to date. The trnR gene exhibit modified secondary structure with the TψC loop completely missing, which might be a putative autapomorphy of S. pamglao mitogenome. Compared with the shallow-water stenopodidean species S. hispidus, the control region of S. pamglao exhibits three characteristics: larger size, higher A + T content, and more tandem repeat sequences. The gene order exhibited difference from the ancestral mitogenome pattern of the Pancrustacea, with 5 tRNA genes rearrangement. The result from BI was agreed with most morphological characters and molecular evidences, revealing that Stenopodidea and Reptantia had the closest relationship, as the sister group of Caridea. Still, the alternative hypothesis supported from ML topology cannot be completely rejected based on the current data. Estimated times revealed that the two stenopodideans families Stenopodidae and Spongicolidae diverged from each other around 122 Mya. The divergence time of spongicolid shrimp is in good agreement with the origin of their hexactinellid hosts (78-144 Mya).
... The R. racovitzae species flock includes four out of five species here sampled, these species are endemic to Antarctica, are morphologically diverse and appear to have evolved rapidly as judged by their poly-or paraphyletic status (observed here) and their biogeographic history. Molecular divergence time estimations resulted in a mean age of *40 ± 20 Ma for crown-group Rossella (Dohrmann et al. 2013). This age accords well with the opening of the Drake Passage (*30 Ma), a geological event that resulted in the final isolation of Antarctica (Lawver and Gahagan 2003) and could have caused the rapid diversification of Rossella in this region. ...
Hexactinellida (glass sponges) are abundant and important components of Antarctic benthic communities. However, the relationships and systematics within the common genus Rossella Carter, 1872 (Lyssacinosida: Rossellidae), are unclear and in need of revision. The species content of this genus has changed dramatically over the years depending on the criteria used by the taxonomic authority consulted. Rossella was formerly regarded as a putatively monophyletic group distributed in the Southern Ocean and the North Atlantic. However, molecular phylogenetic analyses have shown that Rossella is restricted to the Southern Ocean, where it shows a circum-Antarctic and subantarctic distribution. Herein, we provide a molecular phylogenetic analysis of the genus Rossella, based on mitochondrial (16S rDNA and COI) and nuclear (28S rDNA) markers. We corroborate the monophyly of Rossella and provide evidence supporting the existence of one species, namely Rossella antarctica Carter, 1872 and a species flock including specimens determined as Rossella racovitzae Topsent, 1901, Rossella nuda Topsent, 1901, Rossella fibulata Schulze and Kirkpatrick 1910, and Rossella levis (Kirkpatrick 1907).
... (e.g., Manuel et al., 2003). In addition, early sponge fossils have been thought to be phylogenetically derived, for example with the assignment of Cambrian taxa to Hexactinellida, albeit the stem-group due to the differences of these taxa from living members of the class (e.g., Dohrmann et al., 2013). Both of these Botting, 2005), showing preservation of spicules as recrystallised silica (chalcedony); box in (C) shows position of (E). ...
... Within the extant Hexactinellida, there are numerous lineages with very distinctive skeletal architectures, but these may all be morphologically derived: many of the earliest-branching clades include fused spicules, despite an unfused (lyssacine) condition being primitive (Dohrmann et al., 2013). Furthermore, a molecular long branch leading to crown-group Hexactinellida (Dohrmann et al., 2008) suggests substantial evolution and perhaps diversification within the stem group. ...
... On this basis, Cyathophycus Walcott, 1879 was suggested to be an early amphidiscophoran, but more recent work has supported a much deeper origin of that taxon within Silicea, related to the basal stem lineage of demosponges. Assignment of some species by Botting (2004) to the stem group of the Rossellidae has since been criticised on the basis of discordance with later origin estimates based on molecular clock dates (Dohrmann et al., 2013). ...
Sponges are one of the critical groups in understanding the early evolution of animals. Traditional views of these relationships are currently being challenged by molecular data, but the debate has so far made little use of recent palaeontological advances that provide an independent perspective on deep sponge evolution. This review summarises the available information, particularly where the fossil record reveals extinct character combinations that directly impinge on our understanding of high-level relationships and evolutionary origins. An evolutionary outline is proposed that includes the major early fossil groups, combining the fossil record with molecular phylogenetics. The key points are as follows. 1) Crown-group sponge classes are difficult to recognise in the fossil record, with the exception of demosponges, the origins of which are now becoming clear. 2) Hexactine spicules were present in the stem lineages of Hexactinellida, Demospongiae, Silicea and probably also Calcarea and Porifera; this spicule type is not diagnostic of hexactinellids in the fossil record. 3) Reticulosans form the stem lineage of Silicea, and probably also Porifera. 4) At least some early-branching groups possessed biminerallic spicules of silica (with axial filament) combined with an outer layer of calcite secreted within an organic sheath. 5) Spicules are homologous within Silicea, but also between Silicea and Calcarea, and perhaps with Homoscleromorpha. 6) The last common ancestor of extant sponges was probably a thin-walled, hexactine-bearing sponge with biminerallic spicules. 7) The stem group of sponges included tetraradially-symmetric taxa that grade morphologically into Cambrian fossils described as ctenophores. 8) The protomonaxonid sponges are an early-branching group, probably derived from the poriferan stem lineage, and include the problematic chancelloriids as derived members of the piraniid lineage. 9) There are no definite records of Precambrian sponges: isolated hexactine-like spicules may instead be derived from radiolarians. Early sponges had mineralised skeletons and thus should have a good preservation potential: the lack of sponge fossils in Precambrian strata may be due to genuine absence of sponges. 10) In contrast to molecular clock and biomarker evidence, the fossil record indicates a basal Cambrian diversification of the main sponge lineages, and a clear relationship to ctenophore-like ancestors. Overall, the early sponge fossil record reveals a diverse suite of extinct and surprising character combinations that illustrate the origins of the major lineages; however, there are still unanswered questions that require further detailed studies of the morphology, mineralogy and structure of early sponges.
... By providing a framework for the timing of clade origins, molecular time trees can help disambiguate alternative hypotheses about the assignment of fossils to extant higher taxa. For example, Dohrmann et al. (2013) used this approach to evaluate proposed hypotheses about the taxonomic affinity of a number of incompletely preserved glass sponge fossils (Porifera: Hexactinellida). By contrasting probability distributions of molecular clade age estimates against the geological ages of the fossils in questions, they could reject some interpretations proposed by paleontologists. ...
... Although molecular time trees might not provide absolute proofs, such an approach has a great potential because it can spur a process of reciprocal illumination in which paleontologists are urged to rethink their interpretations and examine problematic fossils in more detail; likewise, re-examination of the fossil record can then provide improved calibration information for molecular clock studies. Dohrmann et al. (2013) also found many clades to be 10s to 100s of million years older than their oldest known unambiguous fossils. While such results may raise suspicion in case of taxa with a very well-sampled fossil record, in cases such as glass sponges where the Paleozoic record of extant subgroups is patchy and often ambiguous, molecular age estimates can help narrow down geological intervals that might yield older fossils of certain taxa. ...
... While such results may raise suspicion in case of taxa with a very well-sampled fossil record, in cases such as glass sponges where the Paleozoic record of extant subgroups is patchy and often ambiguous, molecular age estimates can help narrow down geological intervals that might yield older fossils of certain taxa. For example, the interpretation of certain late Cambrian to Lower Ordovician spicules as being true scopules, which would indicate the presence of the subtaxon Sceptrulophora, could not be rejected by Dohrmann et al. (2013) because their age estimates were consistent with the existence of the stem-group of Sceptrulophora at that time. However, the morphology of these microfossils does not allow one to definitely conclude that they are scopules. ...
Molecular paleobiology is a subfield of paleontology that uses molecular biological methods on extant organisms to address geoscientifically relevant questions. Progress in the field was last reviewed in 2007, and here we highlight some of the more recent developments, with a focus on ancient animal evolution, in areas such as the application of molecular clocks to estimate clade ages, the evolution of biomineralization, and the evolution of key traits. We argue that molecular paleobiology has much to offer and will be central to paleontological research and evolutionary biology in general, but we also discuss some remaining challenges and future directions of the discipline.
... Biotas exhibiting Burgess Shale-type (BST) preservation have been reported from the Cambrian and Ordovician of most continents and are critical for the understanding of the early evolution of life, because they conserve a greater diversity beyond typical shelly biotas (e.g., Briggs et al., 1994;Edgecombe and Legg, 2013;Caron et al., 2014). Not only do these important deposits open a window that does not exist under normal fossilization conditions, but the degree of complexity of the fossil lineages also suggests that evolution of several main branches of life was extremely rapid, but there is debate as to whether it began prior to or during the earliest Cambrian (e.g., Dohrmann et al., 2013;Erwin and Valentine, 2013;Landing et al., 2013;Lee et al., 2013). ...
A new Burgess Shale-type Lagerstätte is described from the middle Cambrian (Series 3, Drumian) Rockslide Formation of the Mackenzie Mountains, Northwest Territories, Canada. The Rockslide Formation is a unit of deeper water ramp to slope, mixed carbonate and siliciclastic facies deposited on the northwestern margin of Laurentia. At the fossil-bearing locality, the unit onlaps a fault scarp cutting lower Cambrian sandstones. There it consists of a succession of shale and thick-laminated to thin-bedded lime mudstone, calcareous sandstone, and greenish-colored calcareous mudstone, overlain by shallower water dolostones of the Avalanche Formation, which is indicative of an overall progradational sequence. The Rockslide Formation is of similar age to the Wheeler and Marjum formations of Utah, belonging to the Bolaspidella Biozone. Only two 1 m thick units of greenish mudstone exhibit soft-bodied preservation, with most specimens coming from the lower interval. However, the biota is fairly common but not as diverse as that of other Lagerstätten like the Burgess Shale in its type area. The shelly fauna is dominated by the hyolith Haplophrentis carinatus Matthew, 1899 along with sparse linguliformean brachiopods, agnostoid arthropods, and ptychoparioid trilobites. The non-mineralized biota includes the macrophytic alga Margaretia dorus Walcott, 1911, priapulid worms, and the carapaces of a number of arthropods. The arthropods belong to Isoxys mackenziensis n. sp., Tuzoia cf. T. guntheri Robison and Richards, 1981, Branchiocaris? sp., Perspicaris? dilatus Robison and Richards, 1981, and bradoriids, along with fragments of arthropods of indeterminate affinities. The style of preservation indicates that most soft parts underwent complete biodegradation, leaving just the more resistant materials such as chitinous arthropod cuticles. The range of preservation and similarity to the coeval biotas preserved in Utah suggests that the composition of this Lagerstätte is probably representative of the community living on the relatively deep-water ramp or slope during middle Cambrian time in Laurentia. This would argue that the extraordinary diversity of the Burgess Shale at Mount Field is anomalous.
... Modern Hexasterophora are restricted to hexaster bearing sponges; when microcleres are absent in fossil forms the hexasterophora is restricted to skeletons of Lyssacine or Dictyonine types (Reid 2004). The earliest unambiguous evidence for crowngroup Hexasterophora is the occurrence of dictyonal frameworks, rigid skeletons produced by fusion of hexactine megascleres (in Dohrmann et al. 2013). For this reason, any record of isolated hexaster-type microcleres is important and even more relevant if it is associated with megascleres of a sponge body fossil. ...
... Spicules and microscleres interpreted as sceptrules have been reported from Late Cambrian and Ordovician strata (in Dohrmann et al. 2013). However, their poor preservation and the gap between the next appearances of sceptrules in the Triassic (Donofrio 1991;Krainer & Mostler 1992) raise doubts about the homology of the Palaeozoic and Mesozoic-Recent forms (Dohrmann et al. 2013). ...
... Spicules and microscleres interpreted as sceptrules have been reported from Late Cambrian and Ordovician strata (in Dohrmann et al. 2013). However, their poor preservation and the gap between the next appearances of sceptrules in the Triassic (Donofrio 1991;Krainer & Mostler 1992) raise doubts about the homology of the Palaeozoic and Mesozoic-Recent forms (Dohrmann et al. 2013). ...
Unusually well-preserved spicule assemblages from three Lower to Middle Ordovician localities are examined:
Spitsbergen (Floian-Dapingian), Nevada (Vinini Formation, Dapingian) and Newfoundland (Cow Head Group,
Tremadocian-lower Darriwilian, and Table Head Group, mid-Darriwilian). The recorded diversity increases the knowledge of sponge spicules in the Lower Ordovician and their palaeogeographical distribution. Hexaster type microscleres and scopules, equinate hexactins, pinular hexactins and inflated pentactins and hexactins are the main spicule types amongst the Hexactinellida. Hemidiscs and a possible amphidisc are recorded and can be evidence of the presence of the hexactinellid subclass Amphidiscophora. Oxyasters, C-shaped sigmata and trianes are the main spicule types amongst demosponges. The presence of sigmata and oxyasters can also be evidence of the presence of two main orders of extant demospongids: Sigmatophora (now Spirophorida) and Astrophora. One modified octactinellid spicule type is found from Calcarea. The presence of echinate and pinulate hexactins amongst megascleres suggests a protective functional morphology. These features can be associated with an evolutionary tendency which is seen mainly amongst hexactinellids and demosponges for an efficient occupation of shallower settings and/or a defensive armoury strategy. A newly recorded flat-top pinulate form is also a suitable element for reinforcement or protection of any external surface. Some of the microscleres found can be considered ancient homologues of recent hexasters, sceptrules, hemi/amphidiscs and oxyasters. This work suggests that the microscleres of hexactinellid and demosponge subclasses were already present and significantly diversified in the Early Ordovician. The presence of definite axial canals in scopules provides key evidence for this statement. This finding is significant and confirms the presence of the Sceptrulophora in the early Palaeozoic. The microscleres comes from widely separated Lower Ordovician localities and possess similar forms to those found in Mesozoic microscleres, implying a conservative morphology.
