[dinosaur] Asiatosuchus nanlingensis and Eoalligator chunyii + bird melanin + turtles + croc tracks

Ben Creisler

Some recent non-dino papers (some free):

WU Xiao-Chun, LI Chun & WANG Yan-Yin (2017)

Taxonomic reassessment and phylogenetic test of Asiatosuchus nanlingensis Young, 1964 and Eoalligator chunyii Young, 1964.

Vertebrata PalAsiatica (advance online publication)

http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/201708/t20170803_4839361.html

Free pdf:

http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/201708/P020170803539103919394.pdf

The present paper revalidated Asiatosuchus nanlingensis Young, 1964 and Eoalligator chunyii Young, 1964 in taxonomy based on a detailed comparative study on those relevant specimens. New information derived from this study revealed that A. nanlingensis and E. chunyii were truly distinguishable from each other and therefore, diagnosis was further revised for each of them. A. nanlingensis is large, with a moderately long or a very elongate snout, and characterised mainly by the combination of the following characters such as: the quadrate with a lateral condyle much larger than the medial one, the surangular pinched off before reaching the end of the retroarticular process, the dental margins (at least the posterior portion) of the jaws nearly straight, and the presence of a fossa/sulcus on the lateral surface of the surangular lateral to the mandibular fossa. E. chunyii is a median-sized, short-snouted animal and characterised mainly by the combination of the following characters such as: the condyles of the quadrate similar in size, the dental margins of the jaws strongly concavo-convex, the dentary symphyses very short, the splenial not entering the mandibular symphysis, and the presence of a fossa/sulcus on the lateral surface of the surangular lateral to the mandibular fossa. With new information derived from this study, the phylogenetic relationships of A. nanlingensis and E. chunyii were tested, which did not support the view that the two species formed a monophyletic clade and opposed that E. chunyii could be considered as the synonym of A. nanlingensis.

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Ismael Galván, Jorge García-Campa, and Juan J. Negro (2017)

Complex Plumage Patterns Can Be Produced Only with the Contribution of Melanins.

Physiological and Biochemical Zoology 90(5): 600–604

DOI: 10.1086/693962

http://www.journals.uchicago.edu/doi/10.1086/693962

Free pdf:

http://www.journals.uchicago.edu/doi/pdfplus/10.1086/693962

Birds exhibit an extraordinary diversity of plumage pigmentation patterns. It has been overlooked, however, that complex patterns can be produced only with the contribution of melanins because these are the only pigments under direct cellular control. We tested this hypothesis for the first time examining the plumage patterning of all species of extant birds. Thirty-two percent of species show complex plumage patterns, the vast majority (98%) including the contribution of colors produced by melanins. Only 53 species show complex patterns that do not contain melanin-based colors, and these species display unusual colorations and belong to three families where innovative metabolic modifications of conventional carotenoid pigments have been described. While the adaptive functions of complex plumage patterns remain poorly understood and in most cases are ascribed to fulfill camouflage, our findings indicate that such functions will be understood only by considering the synthesis pathway of melanins.

News:

https://phys.org/news/2017-08-birds.html

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NOT FREE:

Anieli G. Pereira, Juliana Sterli, Filipe R.R. Moreira & Carlos G. Schrago (2017)

Multilocus phylogeny and statistical biogeography clarify the evolutionary history of major lineages of turtles.

Molecular Phylogenetics and Evolution 113: 59-66

doi: https://doi.org/10.1016/j.ympev.2017.05.008

http://www.sciencedirect.com/science/article/pii/S1055790316304316

Despite their complex evolutionary history and the rich fossil record, the higher level phylogeny and historical biogeography of living turtles have not been investigated in a comprehensive and statistical framework. To tackle these issues, we assembled a large molecular dataset, maximizing both taxonomic and gene sampling. As different models provide alternative biogeographical scenarios, we have explicitly tested such hypotheses in order to reconstruct a robust biogeographical history of Testudines. We scanned publicly available databases for nucleotide sequences and composed a dataset comprising 13 loci for 294 living species of Testudines, which accounts for all living genera and 85% of their extant species diversity. Phylogenetic relationships and species divergence times were estimated using a thorough evaluation of fossil information as calibration priors. We then carried out the analysis of historical biogeography of Testudines in a fully statistical framework. Our study recovered the first large-scale phylogeny of turtles with well-supported relationships following the topology proposed by phylogenomic works. Our dating result consistently indicated that the origin of the main clades, Pleurodira and Cryptodira, occurred in the early Jurassic. The phylogenetic and historical biogeographical inferences permitted us to clarify how geological events affected the evolutionary dynamics of crown turtles. For instance, our analyses support the hypothesis that the breakup of Pangaea would have driven the divergence between the cryptodiran and pleurodiran lineages. The reticulated pattern in the ancestral distribution of the cryptodiran lineage suggests a complex biogeographic history for the clade, which was supposedly related to the complex paleogeographic history of Laurasia. On the other hand, the biogeographical history of Pleurodira indicated a tight correlation with the paleogeography of the Gondwanan landmasses.

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Igor G. Danilo, Ekaterina M. Obraztsova, Wen Chen & Jin Jianhua (2017)

The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles.

Journal of Vertebrate Paleontology Article: e1342093

DOI: 10.1080/02724634.2017.1335735.

http://www.tandfonline.com/doi/full/10.1080/02724634.2017.1335735

This paper describes the cranial morphology of Anosteira maomingensis, a turtle of the clade Pan-Carettochelys, based on a skull that is part of a more complete specimen from the middle-upper Eocene Youganwo Formation of Maoming, Guangdong Province, China. The cranial data of An. maomingensis were included in a phylogenetic analysis of pan-carettochelyids, one that was complemented with new codings and characters and also including cranial and non-shell postcranial characters of Kizylkumemys schultzi (Late Cretaceous of Uzbekistan). It also included characters of vertebral scutes of pan-carettochelyids based on a newly proposed nomenclature of vertebral scutes for this group. The result of our phylogenetic analyses supports a recently proposed hypothesis of probable paraphyly of Anosteirinae, Kizylkumemys, Anosteira, and Allaeochelys. In addition, our study summarizes data on cranial morphology of pan-carettochelyid turtles and discusses some aspects of their evolution.

Adán Pérez-García & Sandra D. Chapman (2017)

Identification of Podocnemididae (Pleurodira) in the British record by the first specimen of the coastal Eocenochelus recognized outside Continental Europe.

Proceedings of the Geologists' Association (advance online publication)

doi: https://doi.org/10.1016/j.pgeola.2017.06.001

http://www.sciencedirect.com/science/article/pii/S001678781730086X?via%3Dihub

A turtle shell from the lower Eocene of the Bracklesham Bay (Sussex, England), preserving the partial carapace and the almost complete plastron, is studied here. It is recognized as a member of Pleurodira, being attributed to the coastal podocnemidid Eocenochelus. This systematic identification confirms the presence of Podocnemididae in the British record, corresponding to the first evidence of the presence of this genus of the Erymnochelys group (Erymnochelyinae) outside continental Europe. The finding shows that this lineage of African origin not only reached southern France during the early Eocene, but its dispersion towards higher latitudes also occurred at that time, across epicontinental areas.

James O. Farlow, Nathan J. Robinson, Cory J. Kumagai, Frank V. Paladino, Peter L. Falkingham, Ruth M. Elsey & Anthony J. Martin (2017)

Trackways of the American Crocodile (Crocodylus acutus) in Northwestern Costa Rica: Implications for Crocodylian Ichnology.

Ichnos (advance online publication)

doi: http://dx.doi.org/10.1080/10420940.2017.1350856

http://www.tandfonline.com/doi/full/10.1080/10420940.2017.1350856

We documented trackways of free-living Crocodylus acutus on beaches at the mouths of Tamarindo and Ventanas estuaries, Costa Rica. Our crocodiles had estimated total lengths of 1–3 meters or more. Manus prints have five digits, with digits I–III bearing claw marks. Pes prints have four digits, with claw marks on digits I–III. The pes is plantigrade. Claws generally dig into the substrate. Apart from claw marks, digit I and the heel of the pes are usually the most deeply impressed parts of footprints. Trackways are wide-gauge. Pes prints are usually positioned just behind ipsilateral manus prints of the same set and may overlap them. Manus and pes prints angle slightly outward with respect to the crocodile's direction of movement. Claw-bearing digits of both the manus and pes may create curved, concave-toward-the-midline drag marks as the autopodium is protracted. The tail mark varies in depth and clarity, and in shape from nearly linear to markedly sinuous. Sometimes the tail mark hugs the trackway midline, but sometimes it is closer to, or even cuts across, prints of one side. American crocodile footprints and trackways are similar to those observed in other extant crocodylian species, indicating substantial trackway conservatism across the group.

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