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[dinosaur] Accipitrid skull shape + Eoscapherpeton + diadectomorph tracks + Mesozoic fish shapes

Ben Creisler

Some recent non-dino papers that may be of interest:

Yuchen Sun, Guangdi Sim, Xia Wang, Kangrui Wang & Zihui Zhang (2018)
Geometric morphometric analysis of skull shape in the Accipitridae.
Zoomorphology (advance online publication)
DOI: https://doi.org/10.1007/s00435-018-0406-y

Morphological adaptations for feeding are a conspicuous feature of avian evolution. Accipitrids exhibit a wide range of prey preferences. Skulls of 97 species which were assigned to seven dietary groups in the present study, were compared from the dorsal, lateral, and ventral views using geometric morphometrics. Landmarks were placed on the overall shape of cranium, bill, orbit, nostril, and attachment area for different jaw muscles. The results suggested considerable variations on the shape of bill and cranium, as well as the size of jaw closing muscles, by which can distinguish most of the groups. Scavengers were found to have a more slender and shallower skull, smaller orbits and longer maxilla whereas piscivores have a larger palatine. Mammalivores are characterized by reduced attachment area for the M. adductor mandibular externus superficialis, a relatively large palatine, long maxilla, and caudally positioned quadrate. Insectivores tend to have larger and more anteriorly oriented orbits, a relatively large attachment area for the M. adductor mandibular externus superficialis, and relatively broad and thin bills. Avivores are distinctive in their broad and protrudent caudal cranium. These morphological characteristics have some functional implications, and shed light on further biomechanical research. Moreover, phylogeny and size significantly contribute to skull shape variation.


Free pdf:

Pavel Skutschas, Veniamin Kolchanov, Elizaveta Boitsova, and Ivan Kuzmin (2018)
Osseous anomalies of the cryptobranchid Eoscapherpeton asiaticum (Amphibia: Caudata) from the Late Cretaceous of Uzbekistan.
Fossil Record 21: 159-169Â
doi: https://doi.org/10.5194/fr-21-159-2018, 2018

Osseous anomalies/pathologies in the Late Cretaceous cryptobranchid salamander Eoscapherpeton asiaticum from the Turonian Bissekty Formation of Uzbekistan are analyzed using gross morphological description, microCT, and histologic analysis. These pathologies result from trauma (fractured and subsequently healed dentary and femora; hematoma on femur), possible infection due to trauma (prearticular with exostosis and necrotic cavities; anterior trunk vertebra and fused vertebra with pathological enlargements formed during reactive periosteal growth) and congenital disorders (hemivertebra and fused vertebrae with shortened asymmetrical centra and abnormal arrangements of transverse processes). The origin of the pathologies of two atlantal specimens (enlargement of transverse processes) is unclear. Our report of hemivertebra in Eoscapherpeton is the first occurrence of this congenital pathology in a fossil lissamphibian. The occurrence of several traumatic femoral pathologies in Eoscapherpeton could be a result of intraspecific aggressive behavior. Bone pathologies are described for the first time in fossil salamanders.


Lorenzo Marchetti, Sebastian Voigt & Giuseppe Santi (2018)
A Rare Occurrence of Permian Tetrapod Footprints: Ichniotherium cottae and Ichniotherium sphaerodactylum on the Same Stratigraphic Surface.
Ichnos 25: 2-3
doi: https://doi.org/10.5194/fr-21-137-2018


Ichniotherium Pohlig, 1892 is a principal morphotype of Carboniferous-Permian tetrapod footprints referred to diadectomorphs. Though these tracks are relatively abundant in paleoequatorial regions of Pangea, the Cisuralian Bromacker locality in central Germany, is the only known place with co-occurring Ichniotherium ichnospecies. Ichniotherium cottae Pohlig, 1885 and Ichniotherium sphaerodactylum Pabst, 1895 are well studied from the German fossil site but tracks of the two ichnospecies have reported to be almost exclusively preserved on separate specimens. Here, we describe two rare cases where I. cottae and I. sphaerodactylum tracks occur close each other on the same slab coming from the Bromacker quarry. In order to explain the exceptional occurrence of the two Ichniotherium ichnospecies and the higher relative abundance of I. sphaerodactylum at the Bromacker site, various reasons are discussed, from which the paleoecological ones linked to the time of impression (Hypothesis A) or to the trackmaker areal distribution (Hypothesis B) seem to be the most likely.


John T. Clarke and Matt Friedman (2018)Â
Body-shape diversity in TriassicâEarly Cretaceous neopterygian fishes: sustained holostean disparity and predominantly gradual increases in teleost phenotypic variety.
Paleobiology (advance online publication)
doi: https://doi.org/10.1017/pab.2018.8Â

Comprising Holostei and Teleostei, the ~32,000 species of neopterygian fishes are anatomically disparate and represent the dominant group of aquatic vertebrates today. However, the pattern by which teleosts rose to represent almost all of this diversity, while their holostean sister-group dwindled to eight extant species and two broad morphologies, is poorly constrained. A geometric morphometric approach was taken to generate a morphospace from more than 400 fossil taxa, representing almost all articulated neopterygian taxa known from the first 150 million yearsâroughly 60%âof their history (TriassicâEarly Cretaceous). Patterns of morphospace occupancy and disparity are examined to: (1) assess evidence for a phenotypically âdominantâ holostean phase; (2) evaluate whether expansions in teleost phenotypic variety are predominantly abrupt or gradual, including assessment of whether early apomorphy-defined teleosts are as morphologically conservative as typically assumed; and (3) compare diversification in crown and stem teleosts. The systematic affinities of dapediiforms and pycnodontiforms, two extinct neopterygian clades of uncertain phylogenetic placement, significantly impact patterns of morphological diversification. For instance, alternative placements dictate whether or not holosteans possessed statistically higher disparity than teleosts in the Late Triassic and Jurassic. Despite this ambiguity, all scenarios agree that holosteans do not exhibit a decline in disparity during the Early TriassicâEarly Cretaceous interval, but instead maintain their ToarcianâCallovian variety until the end of the Early Cretaceous without substantial further expansions. After a conservative InduanâCarnian phase, teleosts colonize (and persistently occupy) novel regions of morphospace in a predominantly gradual manner until the Hauterivian, after which expansions are rare. Furthermore, apomorphy-defined teleosts possess greater phenotypic variety than typically assumed. Comparison of crown and stem teleost partial disparity indicates that, despite a statistically significant increase in crown teleost disparity between the Late Jurassic and earliest Cretaceous, stem teleosts remained important long-term contributors to overall teleost disparity during this time.