[Paleontology • 2017] Aphaneramma gavialimimus • A New Extreme Longirostrine Temnospondyl from the Triassic of Madagascar: Phylogenetic and Palaeobiogeographical Implications for Trematosaurids

Aphaneramma gavialimimus Fortuny, Gastou, Escuillié, Ranivoharimanana & Steyer, 2017

 DOI: 10.1080/14772019.2017.1335805   Life reconstruction by Marc Boulay | @JournalSystPal 

Aphaneramma gavialimimus

Fortuny, Gastou, Escuillié, Ranivoharimanana & Steyer, 2017

 DOI: 10.1080/14772019.2017.1335805 
  @JournalSystPal 

Abstract

Trematosaurids form a very large and remarkable clade of Triassic tetrapods (Temnospondyli: Stereospondyli) with a worldwide geographical distribution. Compared with specimens from Europe, Australia or North America, they remain relatively scarce in African rocks, where they are mainly known in the Early Triassic of Madagascar and South Africa. Longirostrine trematosaurids were only known from Madagascar, represented by the genus Wantzosaurus. However, we describe herein a new species of the longirostrine trematosaurid Aphaneramma, Aphaneramma gavialimimus sp. nov., from the Olenekian (Lower Triassic) of Madagascar. This genus was previously known from the Early Triassic of Europe and Asia. Based on a new nearly complete skull, the new species is characterized by a premaxilla-nasal suture anteriorly directed, not contacting the nostrils; choanae completely included within the palatines; the ventral opening of the orbits in the anterior part of the interpterygoid vacuities; a very elongated nasal covering more than 50% of the prenarial length; and an anteriorly widened cultriform process. Aphaneramma gavialimimus sp. nov., with a skull length of about 40 cm, may be one of the largest known trematosaurids. Its inclusion in a new phylogenetic analysis confirms its close affinities with the North American genus Cosgriffius, and clarifies the relationships of trematosaurids in general and lonchorhynchines in particular. The new species also increases the palaeobiodiversity of marine trematosaurs in Gondwana and allows discussing their apparently rapid cosmopolitanism just after the great Permian–Triassic mass extinction.

Keywords: Lonchorhynchinae, Olenekian, palaeobiogeography, Permian–Triassic mass extinction

Figure 1. Aphaneramma gavialimimus sp. nov., Lower Triassic of Madagascar in dorsal view. A, photograph of the holotype UAAmb007; B, photograph of the plastotype MNHN-6703; C, interpretative drawing. 

Systematic palaeontology

Temnospondyli Zittel, 1888

Stereospondyli Zittel, 1888

Trematosauria Romer, 1947 sensu Yates & Warren, 2000

Trematosauroidea Säve-Söderbergh, 1935 sensu Schoch, 2013

Family Trematosauridae Watson, 1919

Subfamily Lonchorhynchinae Säve-Söderbergh, 1935 sensu Steyer, 2002

Aphaneramma Smith Woodward, 1904

Type species. Aphaneramma rostratum Smith Woodward, 1904

(D ‘Lonchorhynchus obergi’ Wiman, 1910) from the early Olenekian of the Sticky Keep of Spitsbergen, Vikinghøgda Formation, Svalbard Archipelago, Norway.

Definition. All taxa sharing a more recent common ancestor with Aphaneramma rostratum than with Cosgriffius campi.

Aphaneramma gavialimimus sp. nov. 

 Etymology. Imitates a gharial (Gavialis gangeticus), due to the general shape similarity with this hyper-longirostral taxon.

Aphaneramma gavialimimus sp. nov., Lower Triassic of Madagascar.

 Life reconstruction by Marc Boulay  (MarcBoulay.fr). 

Josep Fortuny, Stéphanie Gastou, François Escuillié, Lovasoa Ranivoharimanana and J.-Sébastien Steyer. 2017. A New Extreme Longirostrine Temnospondyl from the Triassic of Madagascar: Phylogenetic and Palaeobiogeographical Implications for Trematosaurids. Journal of Systematic Palaeontology.   DOI: 10.1080/14772019.2017.1335805  

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[Paleontology • 2017] Chinlestegophis jenkinsi • Stem Caecilian from the Triassic of Colorado Sheds Light On the Origins of Lissamphibia

Chinlestegophis jenkinsi

Pardo, Small & Huttenlocker, 2017 

news.USC.edu DOI: 10.1073/pnas.1706752114 

 Significance: 

Research into modern amphibian origins is increasingly focusing on the limbless caecilians, a poorly studied group whose pre-Cenozoic fossils are limited to two species. We describe tiny fossils from the Triassic of Colorado with a mixture of traits found in caecilians and extinct Permian–Triassic temnospondyls: Stereospondyli. Computed 3D tomography shows how skull bones organized around internal structures, and we suggest how these may have become fused or simplified in caecilians. The fossils’ association with burrows highlights ecological diversity of Triassic amphibians as well as when and how burrowing evolved in the stereospondyl ancestors of caecilians. Our narrative for research on amphibian origins highlights the importance of stereospondyls, the most numerous and anatomically diverse amphibian group of the Triassic.

Abstract

The origin of the limbless caecilians remains a lasting question in vertebrate evolution. Molecular phylogenies and morphology support that caecilians are the sister taxon of batrachians (frogs and salamanders), from which they diverged no later than the early Permian. Although recent efforts have discovered new, early members of the batrachian lineage, the record of pre-Cretaceous caecilians is limited to a single species, Eocaecilia micropodia. The position of Eocaecilia within tetrapod phylogeny is controversial, as it already acquired the specialized morphology that characterizes modern caecilians by the Jurassic. Here, we report on a small amphibian from the Upper Triassic of Colorado, United States, with a mélange of caecilian synapomorphies and general lissamphibian plesiomorphies. We evaluated its relationships by designing an inclusive phylogenetic analysis that broadly incorporates definitive members of the modern lissamphibian orders and a diversity of extinct temnospondyl amphibians, including stereospondyls. Our results place the taxon confidently within lissamphibians but demonstrate that the diversity of Permian and Triassic stereospondyls also falls within this group. This hypothesis of caecilian origins closes a substantial morphologic and temporal gap and explains the appeal of morphology-based polyphyly hypotheses for the origins of Lissamphibia while reconciling molecular support for the group’s monophyly. Stem caecilian morphology reveals a previously unrecognized stepwise acquisition of typical caecilian cranial apomorphies during the Triassic. A major implication is that many Paleozoic total group lissamphibians (i.e., higher temnospondyls, including the stereospondyl subclade) fall within crown Lissamphibia, which must have originated before 315 million years ago.

Keywords: burrow, Gymnophiona, temnospondyl, tetrapod, Triassic

Chinlestegophis jenkinsi, a tiny subterranean carnivore, is an ancient relative of frogs and salamanders.

(Illustration/Jorge Gonzalez)

Systematic Paleontology. 

Tetrapoda Haworth, 1825

 Temnospondyli Zittel, 1888

Stereospondyli Zittel, 1887

 Chinlestegophis jenkinsi gen. et sp. nov. 

Etymology. Jenkins’s amphibian-serpent from the Chinle.
“Chinle” for the Triassic Chinle Formation; “stego-” (Greek) meaning cover or roof, but commonly applied to temnospondyl amphibians and other early tetrapods; “-ophis” (Greek) meaning serpent. The species name honors paleontologist Farish Jenkins, whose work on the Jurassic Eocaecilia inspired the present study.

Fig. 1. Skulls of Chinlestegophis jenkinsi gen. et sp. nov., DMNH 56658 (A–D) and DMNH 39033 (E–G).
Specimens are shown in dorsal (A and E), ventral (B and G), lateral (C and F), and occipital (D) views. A reconstruction of the skull based on the two specimens is shown in ventral (H), dorsal (I), and left lateral (J) views. All are to scale. a, angular; d, dentary; eo, exoccipital; f, frontal; j, jugal; lep, lateral exposure of palatine; m, maxilla; n, nasal; p, parietal; pal, palatine; pf, postfrontal; pm, premaxilla; po, postorbital; pp, postparietal; prf, prefrontal; ps, parasphenoid; pt, pterygoid; sa, surangular; sp, splenial; sq, squamosal; st, supratemporal; t, tabular.

Fig. 3. Hypothesis of morphological innovations and character transformations along the caecilian stem. Representative skulls are shown in dorsal (left) and ventral (right) views. Characters are color-coded by cranial fusions (red), fossorial characters (yellow), and other classic “caecilian” characters (blue). Some cranial fusions may represent additional adaptations for fossoriality but are treated here separately.
Exemplary taxa are shown in stratigraphic order (left, oldest; right, youngest): the Permian dissorophoid Doleserpeton [redrawn from Sigurdsen and Bolt (34)]; the Early Triassic stereospondyl Lydekkerina [redrawn from Jeannot et al. (35)]; the Middle Triassic brachyopoid Batrachosuchus (based on observation of the holotype of Batrachosuchus browni); d, the Late Triassic Chinlestegophis jenkinsi n. gen. et sp.; the Early Jurassic stem caecilian Eocaecilia [redrawn from Jenkins et al. (2)]; and the crown caecilian Ichthyophis [redrawn from Jenkins et al. (2)]. Skulls are not drawn to scale

Jason D. Pardo, Bryan J. Small and Adam K. Huttenlocker. 2017. Stem Caecilian from the Triassic of Colorado Sheds Light On the Origins of Lissamphibia. Proceedings of the National Academy of Sciences of the United States of America. in press.  DOI: 10.1073/pnas.1706752114

Tiny fossils reveal backstory of the most mysterious amphibian alive today 

The discovery fills a significant gap in the evolutionary history of frogs, toads and other amphibians

 news.USC.edu/123473/tiny-fossils-reveal-backstory-of-the-most-mysterious-amphibian-alive-today/

@incisorial twitter.com/Friedman_Lab/status/876983300841144320

twitter.com/johnhawks/status/877056228081487876

[Paleontology • 2015] The Cranial Morphology of the Temnospondyl Australerpeton cosgriffi (Tetrapoda: Stereospondyli) from the Middle–Late Permian of Paraná Basin and the Phylogenetic Relationships of Rhinesuchidae

  Australerpeton cosgriffi in its environment (Middle–Late Permian [260 million years ago], Rio do Rasto Formation, Paraná Basin, Brazil)

Reconstruction by Rodolfo Nogueira.

DOI:  10.1111/zoj.12339 

  

Abstract

Stereospondyls are a diverse and morphologically distinctive clade of basal tetrapods that rapidly reached a global distribution and high abundance during the Early Triassic. Yet, the first stereospondyls appeared in the Middle–Late Permian of Gondwana, mostly represented by Rhinesuchidae. Australerpeton cosgriffi is a long-snouted representative of the group and one of the most complete temnospondyls known from the Permian of South America. The elements attributed to Au. cosgriffi were recovered from the Middle-Late Permian deposits of the Rio do Rasto Formation (Paraná Basin), in the Serra do Cadeado area of Brazil. Here, we review the cranial anatomy of the species, providing a comparative redescription, new anatomical data and previously unrecognized characters. Australerpeton cosgriffi is nested within Rhinesuchidae based on the anatomy of the tympanic cavity, but its long-snouted condition is unique amongst rhinesuchids. Based on the recovered information and new morphological data, the systematic position of Au. cosgriffi was assessed using a new matrix of 221 characters; of which 196 were selected from previous studies and the remaining are newly proposed. The results show Rhinesuchidae divided into Rhinesuchinae and Australerpetinae. A unique tympanic cavity formed by a well posteroventrally projected tabular horn, stapedial groove, well-developed oblique crest on the pterygoid, and a dorsal pterygoid crest (new term) characterizes the ear region of Rhinesuchidae. Australerpeton cosgriffi is the only undisputed Rhinesuchidae record outside southern Africa and the first long-snouted Stereospondyli, and thus is useful in helping to understand the diversification of the stereospondyls during the Middle/Late Permian of Gondwana.

Keywords: Gondwana; long-snouted rhinesuchid; Palaeozoic; phylogenetics; Rio do Rasto Formation; systematics; Temnospondyli; tympanic cavity

Estevan Eltink, Eliseu V. Dias, Sérgio Dias-da-Silva, Cesar L. Schultz and Max C. Langer. 2015. The Cranial Morphology of the Temnospondyl Australerpeton cosgriffi (Tetrapoda: Stereospondyli) from the Middle–Late Permian of Paraná Basin and the Phylogenetic Relationships of Rhinesuchidae.  Zoological Journal of the Linnean Society. 176(4);   835–860.  DOI: 10.1111/zoj.12339

ResearchGate.net/publication/282870755_The_cranial_morphology_of_the_temnospondyl_Australerpeton_cosgriffi_Tetrapoda_Stereospondyli_from_the_Middle-Late_Permian_of_Parana_Basin_and_the_phylogenetic_relationships_of_Rhinesuchidae

Paleontologists describe giant amphibian that lived 260 million years ago http://agencia.fapesp.br/paleontologists_describe_giant_amphibian_that_lived_260_million_years_ago/22285/

[Paleontology • 2000] Nanolania anatopretia • A new tiny rhytidosteid (Temnospondyli: Stereospondyli) from the Early Triassic of Australia and the possibility of hidden temnospondyl diversity

 Life restoration of Nanolania anatopretia.

by Smokeybjb http://en.wikipedia.org/wiki/Nanolania

A new genus and species of stereospondyl temnospondyl, Nanolcmia anatopretia, is described from the Early Triassic Arcadia Formation (Rewan Group) of Queensland, Australia. N. anatopretia has several character states that suggest it belongs to the group of derived trematosaurian stereospondyls that include the Rhytidosteidae and Brachyopoidea. These include the absence of a lacrimai, an untwisted quadrate ramus of the pterygoid, and a shallow otic notch. It is tentatively referred to the Rhytidosteidae. N. anatopretia is the third temnospondyl taxon from the Arcadia Formation to be represented by a skull less than 50 mm long. The others are the basal stereospondyl Lapillopsis nana, and juveniles of the capitosaurid Parotosuchus aliciae. Given that Lapillopsis nana and Nanolania anatopretia are not known from any larger specimens, and that the temnospondyl fauna from the Arcadia Formation has been well sampled, it is suggested that they are species that never grew large. It seems quite likely that a diverse array of small temnospondyls lived alongside the larger temnospondyls of the Triassic elsewhere in the world but have not been discovered due to biases working against the preservation and collection of small temnospondyl specimens.

 Yates, Adam M. 2000. A new tiny rhytidosteid (Temnospondyli: Stereospondyli) from the Early Triassic of Australia and the possibility of hidden temnospondyl diversity. Journal of Vertebrate Paleontology. 20 (3): 484–489. doi: dx.doi.org/10.1671/0272-4634(2000)020[0484:ANTRTS]2.0.CO;2

http://en.wikipedia.org/wiki/Nanolania