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[dinosaur] Captorhinus kierani, new species (free pdf) + notosuchian burrow from Brazil




Ben Creisler
bcreisler@gmail.com


Some recent non-dino papers:


Free pdf:

Captorhinus kierani sp. nov.

Michael deBraga, Joseph J. Bevitt and Robert R. Reisz (2019)
A New Captorhinid From the Permian Cave System Near Richards Spur, Oklahoma, and the Taxic Diversity of Captorhinus at This Locality.
Frontiers in Earth Science 7:112
doi:Â https://doi.org/10.3389/feart.2019.00112
https://www.frontiersin.org/articles/10.3389/feart.2019.00112/full


The early Permian cave system in the Dolese Brothers Limestone Quarry near Richards Spur, Oklahoma represents a unique depositional environment that has been interpreted as preserving an upland biota. The quarry and the region around it represent Paleozoic cave systems that underwent periods of flooding not unlike present-day conditions that are commonly associated with monsoonal episodes. The Richards Spur locality is particularly rich in captorhinid eureptiles which represent one of the earliest reptilian clades to have evolved a specialized dentition. Although the multiple-tooth rowed Captorhinus aguti is the most abundant captorhinid at Richards Spur, at least one other species has been described (Captorhinus magnus) and assigned to the same genus, but five other captorhinid taxa have also been found. We describe a new member of the genus Captorhinus (Captorhinus kierani) and explore details of the dental anatomy against the two other members of the genus at Richards Spur, C. aguti and C. magnus, as well as with a member of the genus not presently known from Richards Spur (Captorhinus laticeps). Findings suggest that the nature of the ogival dentition described previously as a synapomorphy uniting C. aguti with C. magnus is not supported and we propose a more informative method for differentiating among dental characters within the clade. The discovery of a new species of Captorhinus provides additional evidence for captorhinid taxic diversity at Richards Spur and is supportive of niche partitioning, which is likely associated with reducing intra-specific competition within the clade. In addition, we argue that the captorhinid fossils at Richards Spur likely includes one additional, currently undescribed multiple-tooth rowed form, that renders the current practice of assigning disarticulated cranial remains, specifically dental fragments, to the species C. aguti problematic. Finally, we offer a method for a comprehensive examination of the dental characteristics, which can then be applied to explore taxic diversity at Richards Spur and examine one of the earliest examples of niche specialization. As a consequence of this research, additional insight into exploring biological interactions between Paleozoic taxa can be examined, with an opportunity to shed light on what might have driven these evolutionary processes.

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AgustÃn G. Martinelli,Giorgio Basilici, Lucas E. Fiorelli, Carolina Klock, Joachim Karfunkel, Ariela Costa Diniz, Marcus V.T.Soares, Andrà Marconato, JoÃo Ismaelda Silva, Luiz Carlos B.Ribeiro & Thiago S. Marinho (2019)
Palaeoecological implications of an Upper Cretaceous tetrapod burrow (Bauru Basin; PeirÃpolis, Minas Gerais, Brazil).
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)

Highlights

The first tetrapod burrow from the Late Cretaceous of South America is reported.
The most plausible producer of this burrow is a notosuchian mesoeucrocodylian.
Findings improve knowledge of the ecology of this group.
The burrow occurs in beds with arid palaeoclimate indicators.

Abstract

We describe a globally rare example of a tetrapod burrow from the Upper Cretaceous Bauru Group (Bauru Basin) from PeirÃpolis, Minas Gerais State, Brazil. The sedimentary succession containing the burrow includes a rich vertebrate assemblage comprising fish, podocnemid turtles, mesoeucrocodylians, saurischian dinosaurs, among others. The burrow is composed of an oblique tunnel (~30Â), oval in cross-section, with a horizontal and sub-oval terminal chamber; it is 1.3âm long from the midpoint of its inferred entrance to the midpoint of the bottom of the chamber. It occurs in the upper portion of a sandstone succession, interpreted as a braided channel deposit, and the burrow-fill comprises medium-grained sandstone with mudstone intraclasts derived from fluvial floodplain facies. it is overlain by other fluvial channel deposits. Analyses suggest that the burrow was dug after the filling of the braided channel and during the pedogenesis of its exposed upper surface. Based on burrow morphology and size, the most plausible producer of this burrow is a notosuchian mesoeucrocodylian, such as small to mid-sized notosuchians (e.g., sphagesaurids). The Bauru Group has an extensive fossil record of notosuchians with disparate morphologies, and it is noteworthy that the small-sized notosuchian Labidiosuchus amicum comes from the same unit as the burrow. Moreover, arid to semi-arid conditions have been inferred for fossil-bearing rocks of this unit, and as such the data here presented add to our palaeoecological knowledge of Cretaceous mesoeucrocodylians in Gondwana. Moreover, it constitutes a new Cretaceous record of a tetrapod burrow during a period when such ichnofossils are globally rare.

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