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[dinosaur] Triadobatrachus + Eryops + seymouriamorphs + frogs + more non-dino papers

Ben Creisler

Some recent (and not so recent) non-dino papers that may be of interest:

Eduardo Ascarrunz, Jean-Claude Rage, Pierre Legreneur & Michel Laurin (2016)
Triadobatrachus massinoti, the earliest known lissamphibian (Vertebrata: Tetrapoda) re-examined by µCT scan, and the evolution of trunk length in batrachians.
Contributions to Zoology 85 (2): 201-234

free pdf:


Triadobatrachus massinoti is a batrachian known from a single fossil from the Early Triassic of Madagascar that presents a combination of apomorphic salientian and plesiomorphic batrachian characters. Herein we offer a revised description of the specimen based on X-ray micro-tomography data. We report previously unknown caudal vertebrae, possible mentomeckelians, and hidden parts of other structures. We also confirm the presence of a ventrolateral ledge on the opisthotic, and we rectify some previous interpretations. There are no cervical ribs and the jaw may have had an angular. The presacral region is composed of 15 vertebrae with a unique atlas-axis complex instead of 14 vertebrae with a bipartite atlas. The configuration of the pelvic girdle is not very clear, although it is likely more plesiomorphic than the anuran-like condition previously assumed. Our re-assessment of the saltatorial performance of Triadobatrachus supports the traditional interpretation that this animal was not a specialised jumper. In order to assess the sequence of events in the early evolution of the salientian morphotype, we estimated the ancestral length of the trunk region of batrachians under different hypotheses of lissamphibian relationships and divergence times. Most of our results suggest that some trunk reduction took place before the divergence of caudates and salientians (presumably in the Permian), and that the trunk of Triadobatrachus mostly reflects this ancestral condition. Thus, trunk reduction possibly preceded the anteroposterior elongation of the ilia and the shortening of the tail seen in Triadobatrachus. We also provide an updated review of the data relevant for the use of Triadobatrachus as a calibration constraint in molecular divergence age analyses that meets recently-suggested standards.


Andrej Čerňanský, Florian Witzmann, Jozef Klembara & Anneke H. van Heteren (2016)
The Quadratojugal of Eryops studied by computed tomography and the morphological variability of foramina and canals in the quadratojugal of basal tetrapods.
Anatomical Record 299(8): 1073–1079
DOI: 10.1002/ar.23373

With respect to its large size and abundance, Eryops is an important representative of Permo-Carboniferous basal tetrapods and one of the best-known large temnospondyl amphibians of this period. This taxon forms a significant component of the Early Permian tetrapod fauna of Texas and New Mexico and here we describe a new record of skull remains, the first one from Brushy Creek (30 km northeast of Seymour) in Texas (Petrolia Formation, Wichita Group; Lower Permian – lower Artinskian). Our material, found in 2015, consists of a left nasal, a jaw fragment (premaxilla or maxilla), left quadratojugal fragments, and a partial left mandible. We used computed tomography methods (micro-CT) for imaging both internal and external structures, for the first time, for Eryops. The quadratojugal presented here is exceptional compared to all known basal tetrapods in having four different internal foramina. CT data show that these foramina are interconnected by canals within the bone. This indicates that the morphology of the foramina and the course of the canals in the quadratojugal of basal tetrapods are more variable than hitherto thought. 


Daniel R. Lawver & Frankie D. Jackson (2016)
An accumulation of turtle eggs with embryos from the Campanian (Upper Cretaceous) Judith River Formation of Montana.
Cretaceous Research (advance online publication)
doi: http://dx.doi.org/10.1016/j.cretres.2016.08.012


We propose a new ootaxon, Testudoolithus zelenitskyae.
Embryonic remains from MOR 710 suggest that death occurred close to hatching.
Similarities with Adocus sp. eggs suggest that Adocus likely produced MOR 710.


A weathered accumulation of turtle eggs, interpreted as remnants of a single clutch composed of at least 16 turtle eggs (MOR 710) from the Campanian (Upper Cretaceous) Judith River Formation of north-central Montana, USA, represents a new oospecies Testudoolithus zelenitskyae. This ootaxon is diagnosed by the following unique combination of characters: spherical eggs 34–39 mm in diameter, 660–760 μm thick eggshell, shell unit height-to-width ratio of 3.15:1–5.5:1, and domed shell units. Estimated egg mass indicates that the egg-laying adult likely possessed a carapace 35.0–54.4 cm in length. Similarities between T. zelenitskyae and Adocus sp. eggs, along with comparable body size, suggest that this taxon might have produced MOR 710. One egg exhibits abnormal multilayered eggshell, likely resulting from prolonged egg retention by the female turtle. At least five of these eggs, including the multilayered specimen, preserve embryonic remains that demonstrate a late stage of embryonic development. This suggests that death occurred just prior to hatching.


Lorenzo Marchetti, Eudald Mujal and Massimo Bernardi (2016)
An unusual Amphisauropus trackway and its implication for understanding locomotion.
Lethaia (advance online publication)
DOI: 10.1111/let.12184

Vertebrate ichnology has proved to be a valuable tool for reconstructing tetrapod locomotion. Grounding on 1, the discovery of a new, exceptionally preserved Amphisauropus trackway (Permian Orobic Basin, Northern Italy), showing continuous tail and pedal scratch impressions; and 2, a comparative analysis of track and bony records, we provide a first synapomorphy-based attribution of Amphisauropus tracks to their most plausible producers, seymouriamorph reptiliomorphs, and propose a detailed reconstruction of the locomotion biomechanics in this group. The markedly sinuous and continuous tail impression with a relatively constant width, the curve arrangement of pedal scratches and the inferred position of head, trunk and tail during the locomotion suggest large lateral movements, while vertical movements were nearly absent, consistently with a primitive sprawling gait. We also document the functional prevalence of the hindlimbs and provide a detailed description of femur biomechanics during step cycle. Trackway parameters suggest that the speed was quite slow: a comparison with a large database of Amphisauropus trackways from Italy and Germany proves that this peculiar preservation was gait- and substrate-related, rather than trackmaker-related. In all, this study sheds light on the locomotion of Seymouriamorpha and aimed to contribute to a full integration of track and skeletal data in exploring locomotory biomechanics of extinct tetrapods.


Paleoherpetology special issue  of  open-access journal Fossil Imprint, dedicated to Zdenek V. Spinar


James Gardner (2016)
The fossil record of tadpoles.
Fossil Imprint 72(1-2): 17–44

Anurans are characterized by a biphasic lifecyle, consisting of radically different larval (“tadpole”) and adult (“frog”) morphs. Although the fossil record for tadpoles is more limited compared to the record for frogs, it is more extensive and informative than generally appreciated. The tadpole fossil record consists exclusively of body fossils, often in the form of skeletons with associated soft tissues. Tadpole fossils are known from more than 40 localities of Early Cretaceous (late Berriasian – early Valanginian) to late Miocene age: 24 localities (Early Cretaceous and Cenozoic) in Europe, mostly from deposits of middle Eocene – Miocene age in central and southern Germany and northern Czech Republic; four or five localities (Miocene) in Asia; five localities (latest Cretaceous – Miocene) in continental Africa; and three localities each on the Arabian Plate (Early Cretaceous and Oligocene) and in North America (Eocene) and South America (Campanian and Paleogene). Fossil tadpoles are assignable to at least 16 species belonging to 13 genera and five (possibly as many as seven) families. The tadpole fossil record is dominated by pipoids (Pipidae, Palaeobatrachidae, Rhinophrynidae, and basal pipimorphs), but also includes representatives of Pelobatidae and Ranidae, and possibly Pelodytidae and ?Discoglossidae sensu lato. The tadpole fossil record is limited to lacustrine deposits, yet a significant number of localities in those deposits have yielded size series of tadpole body fossils that have proven informative for examining ontogenetic patterns. Other body fossils suggested at various times to be tadpoles are reviewed: the enigmatic Middle Devonian Palaeospondylus is a fish; the unique holotype specimen of the basal Triassic proto-frog Triadobatrachus is a fully transformed individual, not a metamorphic tadpole; a fossil from the Middle or Late Jurassic of China originally described as a tadpole is an insect; a small skeleton from the Early Cretaceous of Israel originally reported as a tadpole likely is not; and the identity of a fossil preserved within a piece of Miocene Dominican amber and said to be a tadpole hatching from an egg cannot be verified. Extant tadpoles are known to excavate shallow depressions (so-called tadpole nests or holes) in finegrained sediments at the bottom of shallow, low energy water bodies; however, there is no convincing evidence for those structures or any other traces attributable to the activities of tadpoles in the fossil record.


Ana Maria Báez & Raúl Gómez (2016)
Revision of the skeletal morphology of Eodiscoglossus santonjae, an Early Cretaceous frog from northeastern Spain, with comments on its phylogenetic placement.
Fossil Imprint 72(1-2):  67–77

The Mesozoic record for anurans (i.e., crown-clade frogs) in North America extends from the Early Jurassic to terminal Cretaceous. Here we review the record for middle – late Campanian (= Judithian North American Land Mammal Age and ca. 79–73 million years ago) anurans from the North American Western Interior. Judithian anuran fossils (mostly isolated bones) are known from dozens of localities in ten formations, distributed from southern Alberta and Saskatchewan, Canada, southwards into southern Texas, USA. Based largely on distinctive cranial bones, we recognize six or, perhaps, seven species: three named species (Scotiophryne pustulosa, Hensonbatrachus kermiti, and Tyrrellbatrachus brinkmani); three potentially diagnosable species (Theatonius n. sp. and two unnamed new genera and species); and one Scotiophryne-like species (cf. Scotiophryne sp.). On the basis of distinctive maxillae, we also recognize three broad groups of morphs, each of which likely contains multiple, as yet unrecognizable taxa. The familial affinities of those taxa and morphs are uncertain, due to the fragmentary nature of the available specimens. We provisionally recognize two geographic assemblages of Judithian anurans: a northern one encompassing Alberta, Canada and Montana, USA and a southern one encompassing Wyoming, Utah, and New Mexico, USA. The Judithian anuran record contains some species restricted to that interval and other taxa having longer temporal ranges and it documents the first appearances of edentulous anurans (T. brinkmani and Theatonius n. sp.) in the Northern Hemisphere.


Anthony Herrel, Cécile Moureaux, Michel Laurin, Gheylen Daghfous, Kristen Crandell, Krystal Tolley, John Measey, Bike Vanhooydonck & Renaud Boistel (2016)
Frog origins: inferences based on ancestral reconstructions of locomotor performance and anatomy.
Fossil Imprint 72(1-2): 108–116

Frogs are the most species-rich and ecologically diverse group of amphibians and are characterized by a unique body plan including long legs, elongated ilia, and fused caudal vertebrae. Stem anurans such as Triadobatrachus or Czatkobatrachus have been suggested to have used jumping or hopping as part of their locomotor repertoire based on their anatomy. The earliest known true frog, Prosalirus bitis was suggested to have been a proficient jumper. However, data on jumping performance in frogs have never been used to attempt reconstruction of ancestral features at the base of the radiation. Here we provide data on jumping performance (forces and acceleration) in 20 species of extant frogs including representatives of most of the early radiating clades. We next use ancestral character value inferences to assess ancestral features. Our analyses suggest that frog ancestors were of small to medium size, had relatively short limbs, produced rather low jump forces, yet were capable of relatively high acceleration. Given the short limbs and low forces, the unique frog bauplan with a reduced vertebral column and a mobile ilio-sacral joint may not have been an adaptation for powerful jumping


Jozef Klembara (2016)
A new find of discosauriscid seymouriamorph from the Lower Permian of Boskovice Basin in Moravia (the Czech Republic).
Fossil Imprint 72(1-2): 117–121

A preliminary description of a new specimen belonging to the family Discosauriscidae (Seymouriamorpha), Discosauriscidae indet., is presented in this paper. The specimen is partially prepared; only its skull was chemically removed from the matrix and accessible for the study in dorsal aspect. The skull is about 40 mm long and three-dimensionally preserved. The skull differs from all other discosauriscids in three autapomorphic features: 1) distinct ornamentation of the skull roof bones consisting of strongly developed ridges and deep grooves; 2) intertemporal larger than the supratemporal; and 3) anterolateral margin of intertemporal almost straight. These features strongly indicate that the specimen represents a new taxon. However, the taxonomy of this specimen will be evaluated only after its complete preparation.