Carinodens acrodon, new mosasaur from Late Cretaceous of Morocco + Triassic Carnian Pluvial Episode effects in Brazil

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

Recent papers:

Free pdf:

Carinodens acrodon sp. nov.

Nicholas R. Longrich, Xabier Pereda-Suberbiola, Nour-Eddine Jalil and Nathalie Bardet (2025)
A New Species of the Durophagous Mosasaurid Carinodens from the Late Maastrichtian Phosphates of Morocco and Implications for Maastrichtian Mosasaurid Diversity
Diversity 17(1): 25
doi: https://doi.org/10.3390/d17010025
https://www.mdpi.com/1424-2818/17/1/25

Late Cretaceous marine ecosystems saw a major adaptive radiation of mosasaurids, which evolved highly disparate jaw and tooth morphologies to feed on different prey. A striking pattern seen in mosasaurids was a high diversity of durophagous forms. Durophagy likely evolved several times independently in the mosasaurine genera Globidens, Prognathodon, and Carinodens. Carinodens is unusual in having low, rectangular, laterally compressed teeth. The genus is known from around the world, with the species Carinodens minalmamar and C. belgicus previously reported from the Maastrichtian Phosphates of Morocco. Here, we report a new species of Carinodens, C. acrodon, from the same Maastrichtian Phosphates. It is characterized by teeth with tall crowns, triangular apices, and broad bases. Many of the diagnostic features of this species appear to be plesiomorphies, suggesting the persistence of a primitive species of Carinodens into the latest Maastrichtian alongside the more derived C. minalmamar and C. belgicus. The new species contributes to an emerging pattern of mosasaurid hyperdiversity in the late Maastrichtian of Morocco. A revised faunal list, including stratigraphic range extensions of Khinjaria and Stelladens into the latest Maastrichtian of upper Couche III of the Phosphates of Morocco, suggests at least 16 species of mosasauroid coexisted here.


======

Leonardo Corecco, Matthew J. Kohn, Vitor P. Pereira, Linda M. Reynard & Cesar L. Schultz (2024)
Paleoenvironmental and Paleoecological reconstruction of Santa Maria Supersequence units (Middle to Late Triassic, Brazil) based on stable isotope data: Influence of the Carnian Pluvial Episode
Chemical Geology 122589
doi: https://doi.org/10.1016/j.chemgeo.2024.122589
https://www.sciencedirect.com/science/article/abs/pii/S0009254124006697


Highlights

Stable isotope investigation in Dinodontosaurus and Hyperodapedon Assemblage Zones.
Tooth and bone δ13C and δ18O are higher during the Carnian Pluvial Episode.
Precipitation and temperature likely increased.
D. quartacolonia was likely a juvenile P. chiniquensis.

Abstract

Bones and teeth incorporate stable isotopes of C and O from an animal's food and water sources that can provide paleoecological and paleoenvironmental information. In this study, thirty-six samples of fossil bones and teeth were collected from two Triassic allostratigraphic units of the Rio Grande do Sul State, Brazil, and analyzed for δ13C and δ18O values. Specific strata include Pinheiros-Chiniquá Sequence (Late Ladinian/Early Carnian) which includes the Dinodontosaurus Assemblage Zone (15 specimens analyzed) and the basal portion of the Candelária Sequence (Late Carnian) in which the Hyperodapedon Assemblage Zone occurs (21 specimens analyzed). The latter assemblage zone was deposited during the Carnian Pluvial Episode, generally characterized by warmer and wetter conditions. Specimens of tooth enamel from the Dinodontosaurus Assemblage Zone have δ13C values ranging from −10.8 to −7.0 ‰ (VPDB) and δ18O values from 16.3 to 23.5 ‰ (VSMOW). In contrast, specimens from the Hyperodapedon Assemblage Zone have overlapping but generally higher δ13C values ranging from −9.0 to −4.8 ‰ and overlapping but higher δ18O values from 19.7 to 27.4 ‰. Evidently, the Carnian Pluvial Episode coincided with higher δ13C and δ18O values, which could represent warmer (higher δ18O) conditions in this region. Although higher δ13C values can indicate greater aridity, atmospheric δ13C compositions were dramatically (2–3 ‰) higher during the Carnian than the earlier Middle Triassic epoch. Within uncertainties, the 2 ‰ increases to fossil δ13C values could be consistent with either constant or increased precipitation. Climate change during the Late Triassic could have helped drive profound faunal turnover during this episode, including dinosaur evolution and diversification.

====

====