An Early Permian varanodontine varanopid (Synapsida: Eupelycosauria) from the Richards Spur locality, Oklahoma

Maddin, Hillary C.; Evans, David C.; Reisz, Robert R.

doi:10.1671/0272-4634(2006)26[957:aepvvs]2.0.co;2

Cited by 47 publications

(61 citation statements)

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“…Cotylorhynchus romeri is therefore not an appropriate taxon for assessing polarity in varanopid axial spine mor− phology. Systematic implications.-The main systematic and phylo− genetic debate in varanopids centres on the diversity of South African specimens and the phylogenetic position of Elliot− smithia longiceps (Dilkes and Reisz 1996;Reisz et al 1998;Modesto et al 2001;Reisz and Dilkes 2003;Maddin et al 2006;Reisz and Modesto 2007;Botha−Brink and Modesto 2009;Campione and Reisz 2010). This debate arises from different interpretations of cranial morphological in the holo− type material of E. longiceps, and the possibility that there are more than one species of varanopid co−existing in the late Middle Permian of South Africa.…”

Section: B Cotylorhynchus Romerimentioning

confidence: 99%

“…Among basal synapsids, atlantal and axial morphology is well known in Ophiacodon, Dimetrodon (Romer and Price 1940), and Secodontosaurus . In varanopids, it has been briefly described for some taxa, such as Varanops brevirostris and Elliotsmithia longi− ceps (Williston 1911;Reisz et al 1998;Modesto et al 2001) and potential variation between varanopid taxa was identified by Maddin et al (2006). The varanopid atlas−axis complex is preserved in several species and therefore this clade allows for a detailed comparative study of the atlas−axis, with implica− tions for varanopid systematics and diversity.…”

Section: Introductionmentioning

confidence: 99%

“…Varanopidae include three possible basal species, Archaeo− venator hamiltonensis Dilkes, 2003, Apsisaurus witteri Laurin, 1991, and Pyozia mesenensis Anderson and Reisz, 2004, although the assignment of the latter to Varano− pidae has been questioned (Maddin et al 2006;Campione and Reisz 2010). Varanopids generally include two main clades, Mycterosaurinae (Mycterosaurus longiceps Williston, 1915, Mesenosaurus romeri Efremov, 1938, and Heleosaurus schol− tzi Broom, 1907, and Varanodontinae (Varanops brevirostris [Williston, 1911], Varanodon agilis Olson, 1965, Aerosaurus wellesi Langston and Reisz, 1981, and Watongia meieri Olson, 1974, though the monophyly of mycterosaurines has recently been questioned .…”

Section: Introductionmentioning

confidence: 99%

“…The most complete description of a varanopid atlas−axis complex is that of the varanodontine Varanops brevirostris (Williston 1911;Maddin et al 2006;Campione and Reisz 2010). Less is known about mycterosaurines, in which the only description is based on a partial axis Mycterosaurus (Reisz et al 1997).…”

Section: Introductionmentioning

confidence: 99%

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Morphology and Evolutionary Significance of the Atlas-Axis Complex in Varanopid Synapsids

Campione¹,

Reisz²

2011

Acta Palaeontologica Polonica

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BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses.Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne's Terms of Use, available at www.bioone.org/page/terms_of_use.Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. The atlas−axis complex has been described in few Palaeozoic taxa, with little effort being placed on examining variation of this structure within a small clade. Most varanopids, members of a clade of gracile synapsid predators, have well pre− served atlas−axes permitting detailed descriptions and examination of morphological variation. This study indicates that the size of the transverse processes on the axis and the shape of the axial neural spine vary among members of this clade. In particular, the small mycterosaurine varanopids possess small transverse processes that point posteroventrally, and the axial spine is dorsoventrally short, with a flattened dorsal margin in lateral view. The larger varanodontine varanopids have large transverse processes with a broad base, and a much taller axial spine with a rounded dorsal margin in lateral view. Based on outgroup comparisons, the morphology exhibited by the transverse processes is interpreted as derived in varanodontines, whereas the morphology of the axial spine is derived in mycterosaurines. The axial spine anatomy of Middle Permian South African varanopids is reviewed and our interpretation is consistent with the hypothesis that at least two varanopid taxa are present in South Africa, a region overwhelmingly dominated by therapsid synapsids and parareptiles.

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Section: B Cotylorhynchus Romerimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Morphology and Evolutionary Significance of the Atlas-Axis Complex in Varanopid Synapsids

Campione¹,

Reisz²

2011

Acta Palaeontologica Polonica

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“…The Lower Permian Dolese Brothers Limestone Quarry locality near Richard Spur in Oklahoma is the most productive fossil site for Paleozoic terrestrial ecosystems, and has yielded more than 40 fully terrestrial tetrapod taxa, many of which are endemic to the locality (Anderson and Bolt, 2013;Anderson and Reisz, 2003;Bolt, 1969Bolt, , 1977Fröbisch and Reisz, 2008;Fröbisch and Reisz, 2012;Maddin et al, 2006;Reisz, 2005;Sullivan and Reisz, 1999;Sullivan et al, 2000). The vertebrate fossils are preserved in clay-rich continental sediments of Artinskian age (Lucas, 2006;Woodhead et al, 2010) that form infills within the Ordovician Arbuckle Limestone.…”

Section: Introductionmentioning

confidence: 99%

New specimen of <i>Cacops woehri</i> indicates differences in the ontogenetic trajectories among cacopine dissorophids

2015

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Abstract. The Lower Permian Dolese locality has produced numerous exquisitely preserved tetrapod fossils representing members of a lower Permian upland fauna. Therein, at least nine taxa of the clade Dissorophoidea, ranging in size from the large predaceous trematopid Acheloma to the miniaturized amphibamid Doleserpeton, highlight the great taxic and ecological diversity of this anamniote clade. Here we describe a large specimen of the dissorophid Cacops woehri, which was previously only known from the juvenile or subadult holotype skull. Another member of the genus Cacops present at the Dolese locality, Cacops morrisi, is also represented by specimens spanning juvenile, subadult, and adult stages, allowing for a comparison of morphological changes taking place in the late phases of the ontogenetic trajectory of cacopine dissorophids. The new find shows that, in contrast to C. morrisi and C. aspidephorus, C. woehri only undergoes relatively subtle changes in skull morphology in late ontogeny and retains the overall more gracile morphology into adult stages. This includes retention of the rather shallow skull shape as well as a pattern of sculpturing consisting of elongate ridges and grooves and a large occipital flange. This suggests somewhat different functional demands in C. woehri than in other known species of Cacops, possibly associated with a different ecology paralleling the great taxic diversity of dissorophoids at the Dolese locality.

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A redescription of Orovenator mayorum (Sauropsida, Diapsida) using high‐resolution μCT, and the consequences for early amniote phylogeny

Ford

Benson

2018

Papers in Palaeontology

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The earliest known neodiapsid Orovenator mayorum from the lower Permian of Oklahoma is redescribed using high‐resolution μCT, revealing remarkable details of the skull anatomy. Our findings are relevant to both palaeoecology (suggesting burrowing and nocturnality) and phylogeny. Orovenator and other sauropsids share at least 16 character states with varanopids, many of which were not recognized by previous studies. These include a rounded subnarial shelf of the premaxilla, a posterodorsal extension of the external naris, the asymmetrical bifurcation of the anterior vomer, and a prominent dorsomedial shelf of the surangular. This exceptional degree of similarity between Orovenator and varanopids (a nominally synapsid clade) questions our current understanding of relationships among early amniotes. We test this by including Orovenator in a phylogenetic data matrix used in an earlier study to differentiate between early diapsids and synapsids, and find a monophyletic clade of Orovenator + varanopids within Diapsida. Recent phylogenetic research on early amniote evolution has focused on resolving intra‐clade affiliations rather than the interrelationships of major taxonomic groups. Nevertheless, the relative incompleteness of existing phylogenetic character lists for early amniotes can only be remedied by detailed cross‐clade assessment. We therefore suggest that early amniote relationships require further scrutiny before we can confidently accept or reject our new phylogenetic hypothesis.

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An Early Permian varanodontine varanopid (Synapsida: Eupelycosauria) from the Richards Spur locality, Oklahoma

Cited by 47 publications

References 16 publications

Morphology and Evolutionary Significance of the Atlas-Axis Complex in Varanopid Synapsids

Morphology and Evolutionary Significance of the Atlas-Axis Complex in Varanopid Synapsids

New specimen of <i>Cacops woehri</i> indicates differences in the ontogenetic trajectories among cacopine dissorophids

A redescription of Orovenator mayorum (Sauropsida, Diapsida) using high‐resolution μCT, and the consequences for early amniote phylogeny

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An Early Permian varanodontine varanopid (Synapsida: Eupelycosauria) from the Richards Spur locality, Oklahoma

Cited by 47 publications

References 16 publications

Morphology and Evolutionary Significance of the Atlas-Axis Complex in Varanopid Synapsids

Morphology and Evolutionary Significance of the Atlas-Axis Complex in Varanopid Synapsids

New specimen of &lt;i&gt;Cacops woehri&lt;/i&gt; indicates differences in the ontogenetic trajectories among cacopine dissorophids

A redescription of Orovenator mayorum (Sauropsida, Diapsida) using high‐resolution μCT, and the consequences for early amniote phylogeny

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New specimen of <i>Cacops woehri</i> indicates differences in the ontogenetic trajectories among cacopine dissorophids