Ben Creisler
Some recent non-dino papers:
Eopelecanus aegyptiacus gen. et sp. nov.
Joseph J. El Adli, Jeffrey A. Wilson Mantilla, Mohammed Sameh M. Antar & Philip D. Gingerich (2021)
The earliest recorded fossil pelican, recovered from the late Eocene of Wadi Al-Hitan, Egypt.
Journal of Vertebrate Paleontology Article: e1903910
doi:
https://doi.org/10.1080/02724634.2021.1903910 https://www.tandfonline.com/doi/full/10.1080/02724634.2021.1903910The Paleogene record of pelicans (Pelecanidae) is represented at present by a single early Oligocene specimen from southeastern France. Here we describe a new pelecanid from the early Priabonian portion of the Birket Qarun Formation within the Wadi Al-Hitan World Heritage Site in Egypt. This specimen, a nearly complete right tibiotarsus, is the first definitive pelecanid recovered from Eocene strata. The tibiotarsus is remarkably similar to those of known Pelecanus species, but sufficiently different to warrant designation as the new genus and species Eopelecanus aegyptiacus. This represents the oldest pelican described to date and extends the pelecanid fossil record by ca. 6 million years.
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Despite the general perception that crocodilians exhibit indeterminate growth, recent long-term field studies and laboratory investigations have independently suggested that growth in these animals is determinate. In this study, we had the unique opportunity to examine skeletal growth in a wild adult American alligator (Alligator mississippiensis) based on change in body length measurements (snout-vent length) in the field and confirm these findings using osteohistological analyses (presence/absence of an external fundamental system [EFS]) of long bones. The alligator was captured and measured five times over 7âyears and exhibited no discernable growth during that period, suggesting skeletal maturity had been attained at or prior to its first capture. Our field assessment of determinate growth in this alligator was osteohistologically confirmed by the presence of an EFS in the animal's humerus, femur, tibia, and fibula. To our knowledge, this study is the first to report determinate growth in a wild crocodilian using both field and laboratory methods, providing further evidence of this growth pattern in crocodilians.
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Free pdf:
Daniel J Paluh, Karina Riddell, Catherine M Early, Maggie M Hantak, Gregory FM Jongsma, Rachel M Keeffe, Fernanda MagalhÃes Silva, Stuart V Nielsen, MarÃa Camila Vallejo-Pareja, Edward L Stanley & David C Blackburn (2021)
Rampant tooth loss across 200 million years of frog evolution.
eLife 10:e66926
DOI: 10.7554/eLife.66926
https://elifesciences.org/articles/66926Teeth are present in most clades of vertebrates but have been lost completely several times in actinopterygian fishes and amniotes. Using phenotypic data collected from over 500 genera via micro-computed tomography, we provide the first rigorous assessment of the evolutionary history of dentition across all major lineages of amphibians. We demonstrate that dentition is invariably present in caecilians and salamanders, but teeth have been lost completely more than 20 times in frogs, a much higher occurrence of edentulism than in any other vertebrate group. The repeated loss of teeth in anurans is associated with a specialized diet of small invertebrate prey as well as shortening of the lower jaw, but it is not correlated with a reduction in body size. Frogs provide an unparalleled opportunity for investigating the molecular and developmental mechanisms of convergent tooth loss on a large phylogenetic scale.