Latest Articles from Fossil Record Latest 3 Articles from Fossil Record https://fr.pensoft.net/ Fri, 29 Mar 2024 10:36:53 +0200 Pensoft FeedCreator https://fr.pensoft.net/i/logo.jpg Latest Articles from Fossil Record https://fr.pensoft.net/ The new problem of Chinlestegophis and the origin of caecilians (Amphibia, Gymnophionomorpha) is highly sensitive to old problems of sampling and character construction https://fr.pensoft.net/article/109555/ Fossil Record 27(1): 55-94

DOI: 10.3897/fr.27.e109555

Authors: David Marjanović, Hillary C. Maddin, Jennifer C. Olori, Michel Laurin

Abstract: The description of the small Late Triassic temnospondyl Chinlestegophis ushered in a potentially radically new understanding of the origins of the extant amphibian clades. Together with the fragmentary Rileymillerus, Chinlestegophis was argued to link extant caecilians to Permo-Triassic stereospondyl temnospondyls rather than to frogs and salamanders (and through them to amphibamiform temnospondyls or to brachystelechid and lysorophian “lepospondyls”). We critically review the comparative description of Chinlestegophis and phylogenetic analyses of previous studies. Most of the features previously interpreted to be shared by caecilians, Chinlestegophis and/or other stereospondyls have different distributions than scored in the analysis. We also find no evidence for an incipient tentacular sulcus in Chinlestegophis, and note that its vertebrae, unreduced ribs and dermal shoulder girdle are unlike those of any extant amphibians (nor their likely sister group, Albanerpetidae). Furthermore, the original matrices contain misscores accreted over more than a decade that likewise influence the results. Some features are coded as multiple redundant characters: the double toothrow of Chinlestegophis, other stereospondyls, and caecilians is represented as seven characters. Analysis of the unmodified matrix yields much less resolution than originally reported, and tree topology is altered by a small change to the taxon sample (the addition of Albanerpetidae), limited revisions of irreproducible scores, and ordering the most obviously clinal characters; any one of these changes removes Chinlestegophis from Lissamphibia, and confirms it as a stereospondyl.

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Research Article Wed, 10 Jan 2024 14:33:51 +0200
An alternative interpretation of small-bodied turtles from the “Middle Purbeck” of England as a new species of compsemydid turtle https://fr.pensoft.net/article/85334/ Fossil Record 25(2): 263-274

DOI: 10.3897/fr.25.85334

Authors: Walter G. Joyce, Jason R. Bourque, Vincent Fernandez, Yann Rollot

Abstract: A series of small-sized fossil turtles were collected from Beckles’ Pit, Durlston Bay, Dorset, United Kingdom in 1856 from a sediment package referable to the Early Cretaceous (Berriasian) Purbeck Group. The two primary accounts that previously documented these turtles concluded that they represent the juveniles of the coeval early pleurosternid Pleurosternon bullockii. A brief, third account, however, suggested that these may represent a new species of compsemydid turtle. We here highlight a series of discrete morphological characters that consistently distinguish the small-bodied turtles from Beckles’ Pit from large-bodied Pleurosternon bullockii, in particular the arrangement of the bones and scutes along the anterior margin of the shell. As these characters are otherwise used to diagnose new species of turtles, in particular compsemydids, and to establish the phylogeny of fossil turtles, we side with the latter interpretation and name a new taxon of early compsemydid, Tongemys enigmatica gen. et sp. nov. The early record of compsemydid is restricted to the Early Cretaceous of Europe, but is extremely fragmentary. We suggest that this may be a bias towards the collection and identification of small turtle remains, but also that a re-study of Early Cretaceous continental turtle faunas is likely to yield further material.

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Research Article Wed, 17 Aug 2022 21:46:31 +0300
Amphibian and reptilian fauna from the early Miocene of Echzell, Germany https://fr.pensoft.net/article/83781/ Fossil Record 25(1): 99-145

DOI: 10.3897/fr.25.83781

Authors: Davit Vasilyan, Andrej Čerňanský, Zbigniew Szyndlar, Thomas Mörs

Abstract: The present study describes a rich amphibian and reptilian assemblage from the early Miocene locality Echzell, Germany. It consists of one allocaudate, five salamander, five frog, one gecko, chamaeleonids, anguine lizards, one lacertid, one skink and five snake taxa. The entire herpetofauna of Echzell is represented by genera and/or families very broadly known from the early Miocene of Europe. Contrary to other early Miocene herpetofaunas, the Echzell assemblage includes surprisingly only one form of crocodile-newts (Chelotriton). The Echzell Palaeobatrachus robustus represents the youngest record of the species and extends its stratigraphic range to the late early Miocene. Regarding chameleons, the frontal is partly preserved, but represents the first described frontal of the extinct species Chamaeleo andrusovi. The only anguine lizard that can be identified in the assemblage is represented by a new genus and species Smithosaurus echzellensis. Our phylogenetic analyses consistently recovered it as the sister taxon to either [Ophisauriscus quadrupes + Ophisaurus holeci] + [Anguis + Ophisaurus] (in the first analysis) or [Anguis + Ophisaurus] (in the second analysis). However, the results are based on limited fossil material – the parietal – and the support for the clade is very low. Thus, the interpretation of the Smithosaurus relationship among anguines needs to be taken with caution and has to be tested in further studies. Among snakes, Natrix longivertebrata represents the oldest record of the species and extends the stratigraphic range of this fossil snake back to the early Miocene. In addition, we provide here a broader comparison of the Echzell amphibian and reptilian assemblage with their European records for the MN3 and MN4 biostratigraphical units. Besides that, the entire herpetofauna of Echzell includes very broadly known early Miocene European forms. Remains of other groups of the same period such as Bufonidae, Hylidae, Pelodytidae, Amphisbaenia, Varanidae, Cordylidae, Pseudopus, are not found in the material available to us. We also conclude that the amphibian and reptilian fossil record across MN3–MN4 is significantly biased by taphonomic and/or environmental conditions. The amphibian and reptilian assemblage of Echzell is rich in forms living in humid and warm environments with forested areas, permanent water bodies and also some open habitats. The following climatic parameters can be reconstructed based on the herpetofauna: a mean annual temperature of 17.4–28.8 °C, minimal warm month temperature 18–28.3 °C, minimal cold month temperature 8–22.2 °C, and mean annual precipitation with a value of 791±254 mm.

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Research Article Tue, 10 May 2022 18:11:12 +0300