Ben Creisler
Recent non-dino papers:
Free pdf:
Anthony J. Fuentes, William C. Clyde, Ken Weissenburger, Antoine Bercovici, Tyler R. Lyson, Ian M. Miller, Jahandar Ramezani, Vincent Isakson, Mark D. Schmitz & Kirk R. Johnson (2019)
Constructing a time scale of biotic recovery across the Cretaceous-Paleogene boundary, Corral Bluffs, Denver Basin, Colorado, U.S.A.
Rocky Mountain Geology 54 (2): 133â153
doi:
https://doi.org/10.24872/rmgjournal.54.2.133https://pubs.geoscienceworld.org/uwyo/rmg/article/54/2/133/579762
The Cretaceous-Paleogene (K-Pg) boundary interval represents one of the most significant mass extinctions and ensuing biotic recoveries in Earth history. Earliest Paleocene fossil mammal faunas corresponding to the Puercan North American Land Mammal Age (NALMA) are thought to be highly endemic and potentially diachronous, necessitating precise chronostratigraphic controls at key fossil localities to constrain recovery dynamics in continental biotas following the K-Pg mass extinction. The Laramide synorgenic sedimentary deposits within the Denver Basin in east-central Colorado preserve one of the most continuous and fossiliferous records of the K-Pg boundary interval in North America. Poor exposure in much of the Denver Basin, however, makes it difficult to correlate between outcrops. To constrain fossil localities in coeval strata across the basin, previous studies have relied upon chronostratigraphic methods such as magnetostratigraphy. Here, we present a new high-resolution magnetostratigraphy of 10 lithostratigraphic sections spanning the K-Pg boundary interval at Corral Bluffs located east of Colorado Springs in the southern part of the Denver Basin. Fossil localities from Corral Bluffs have yielded limited dinosaur remains, mammal fossils assigned to the Puercan NALMA, and numerous fossil leaf localities. Palynological analyses identifying the K-Pg boundary in three sections and two independent, but nearly identical, 206Pb/238U age estimates for the same volcanic ash, provide key temporal calibration points. Our paleomagnetic analyses have identified clear polarity reversal boundaries from chron C30n to chron C28r across the sections. It is now possible to place the fossil localities at Corral Bluffs within the broader basin-wide chronostratigraphic framework and evaluate them in the context of K-Pg boundary extinction and recovery.
====
Free pdf:
Cardichelyon rogerwoodi is an enigmatic fossil turtle from the late Paleocene to early Eocene of North America. Previous analyses suggested affiliation with Testudinoidea, in particular the big-headed turtle Platysternon megacephalum, based on the presence of multiple musk-duct foramina and a large head. We here highlight previously undocumented characteristics for this turtle, notably the presence of short costiform processes, a rib-like axillary process, and a posterior plastral hinge. Phylogenetic analysis places Cardichelyon rogerwoodi within Testudinoidea, but the exclusion of testudinoids suggest an affiliation with Dermatemydidae. Using consilience with external data we favor placement within Kinosternoidea. Cardichelyon rogerwoodi is therefore an aberrant, hinged kinosternoid that developed in situ in North America during the Paleocene long before the arrival of testudinoids on this continent in the early Eocene.
====
Alatochelon myrteum gen. et sp. nov.Â
Herein, we describe Alatochelon myrteum gen. et sp. nov., a large tortoise from the postâMessinian (lower Pliocene) of the area of Puerto de la Cadena (Region of Murcia), Spain. The new taxon cannot be attributed to Titanochelon, which represented the only lineage of large tortoises previously recognized in the Neogene record of Europe. Alatochelon myrteum shows African affinities, especially with the extant African spurred tortoise Centrochelys sulcata. Although close phylogenetic relationships have previously been recognized among some tortoises of both continents, the dispersal of this lineage had always been proposed as having occurred in only one direction: from Europe to Africa. The dispersal of the lineage including the new Spanish form and Centrochelys sulcata from Africa to Europe is proposed here. This proposal is compatible with those previously recognized for some lineages of mammals also found in Puerto de la Cadena, identified as African lineages that probably reached Europe during the Messinian Salinity Crisis event. An African origin is also proposed for the lineage of Titanochelon. Therefore, the two lineages of large derived testudinids (i.e. Geochelona) recognized in the European record experienced diachronic dispersal events from Africa to Europe: that to which Alatochelon belongs probably during the Messinian and the other much earlier, at the beginning of the Miocene or before.
===
The lowermost Triassic unambiguous temnospondyl tracks are recovered from Vellberg.
Capitosaur stereospondyls are the most probable trackmakers.
Only tetradactyl manus tracks: forelimbs prevailing over hindlimbs in locomotion
Locomotion of temnospondyls similar to present-day swimming crocodiles
Low probability of amphibian track preservation: environment and mode of locomotion
Abstract
Triassic temnospondyl amphibian tracks are relatively rare, in contrast with the body fossil record. Herein we report temnospondyl tracks from the base of the Anthrakonitbank carbonate bed, within the upper Middle Triassic Lower Keuper succession (Erfurt Formation) in the Vellberg fossil-lagerstÃtte of southern Germany. The sedimentary succession comprises restricted marine deposits, and the track-bearing layer includes microbial mats covering thin bone-beds. The ichnological material includes >20 footprints, four of which are arranged in a trackway, and all footprints comprise manus impressions with no pes preserved. The combination of characters, such as tetradactyl clawless manus impressions, relative digit length and angulation, and trackway with low pace angulation, are different from any known tetrapod ichnotaxon. While the scarcity of material precludes a confident ichnotaxonomy, comparison with the autopodia in the body fossil record suggests capitosaur stereospondyls as the most probable trackmakers. Ichnological and sedimentological features indicate that the trackmakers displayed a walking-swimming locomotion, with a sprawling posture, only touching the substrate with the forelimbs, as seen in present-day swimming crocodiles. The Vellberg tetrapod tracks reported here contribute to our knowledge of the Triassic ichnological record, as well as the life style and habitats of temnospondyls.
===
Novikov I. V., Haiduk P. A., Gribanov A. V., Ivanov Ð. N., Novikov Ð. V., Starodubtseva I. A.
The Earliest Case of Neoplastic Bone Lesion in Tetrapods.
Paleontological Journal 54(1): 66-69 (in Russian)
DOI: 10.31857/S0031031X20010092
https://elibrary.ru/item.asp?id=41695139The results of the examination of a bone neoplastic lesion in lower jaw of Early Triassic temnospondyl amphibian Benthosuchus korobkovi from Tikhvinskoye locality (Yaroslavl region, Rybinsk district; Early Olenekian) are presented. Multispiral computer tomography confirmed with a sufficient degree of confidence the neoplastic nature of the lesion; the most probable diagnosis: non-odontogenic osteoma. Hemangioma and bone fibrous dysplasia are also possible.
===
Free pdf:
Zhuo Chen & John J. Wiens (2020)
The origins of acoustic communication in vertebrates.
Nature Communications 11, Article number: 369
doi:ÂÂ
https://doi.org/10.1038/s41467-020-14356-3https://www.nature.com/articles/s41467-020-14356-3Â
Free pdf:
https://www.nature.com/articles/s41467-020-14356-3.pdfÂ
Acoustic communication is crucial to humans and many other tetrapods, including birds, frogs, crocodilians, and mammals. However, large-scale patterns in its evolution are largely unstudied. Here, we address several fundamental questions about the origins of acoustic communication in terrestrial vertebrates (tetrapods), using phylogenetic methods. We show that origins of acoustic communication are significantly associated with nocturnal activity. We find that acoustic communication does not increase diversification rates, a surprising result given the many speciation-focused studies of frog calls and bird songs. We also demonstrate that the presence of acoustic communication is strongly conserved over time. Finally, we find that acoustic communication evolved independently in most major tetrapod groups, often with remarkably ancient origins (~100â200 million years ago). Overall, we show that the role of ecology in shaping signal evolution applies to surprisingly deep timescales, whereas the role of signal evolution in diversification may not.