Denazinemys

Denazinemys Temporal range: Late Cretaceous, 75–66  Ma PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Pantestudines
Clade:	Testudinata
Clade:	† Paracryptodira
Family:	† Baenidae
Genus:	† Denazinemys Lucas and Sullivan, 2006
Species:	†D. nodosa
Binomial name
†Denazinemys nodosa (Gilmore, 1916)
Synonyms [1]
Baena nodosaGilmore, 1916

Denazinemys was a genus of baenid turtle that lived in the present-day southwestern United States during the Late Cretaceous. The type and only known species is D. nodosa.

History of discovery

The holotype specimen, which D. nodosa was based on, USNM 8345, consists of a partial carapace and plastron from the upper Campanian-aged Kirtland Formation. Numerous shell fragments from various formations were also assigned to Denazinemys nodosa, based on the welted structure of the shell surface. However, with the exception of relatively complete specimens from the Fruitland Formation and the Kaiparowits Formation, Spicher et al. (2023) questioned the attributed specimens from other formations, as they are too fragmentary to distinguish differences in the structure of the welted shell surface. ^[2] As it is not yet possible to identify these fragments precisely (several species of Baenidae having this same feature on their shell surface), the researchers restricted Denazinemys nodosa to the Upper Campanian. ^[2] In 2025, other specimens assigned to D. nodosa have been reported from the Aguja Formation and the Javelina Formation. ^[3]

Description

Previously, Scabremys ornata was assigned to Denazinemys as D. ornata. Below are the features found in Denazinemys distinguishing the two genera: ^[1]

• a carapace that is sub-triangular with widest dimension posteriorly;
• prepleurals present and touching the first vertebrae medially;
• the first vertebrae an irregular hexagonal shape with the greatest width posteriorly, contacting anterior second vertebrae;
• extracervicals lateral to the primary cervicals, the cervicals being sub-divided;
• and carapace nodes irregular and not forming distinct ridges.

Classification

Denazinemys is a baenid along with Plesiobaena , Boremys , Scabremys, Baena and Chisternon . ^[1]

Below is a cladogram made by Sullivan et al. in 2013 showing the relations of Denazinemys: (note: Boremys pulchra is partly a junior synonym of Boremys grandis) ^[1]

Baenidae	hypothetical ancestor Neurankylus eximius Trintichelys hiatti Baenodda Plesiobaena antiqua Scabremys ornata Boremys pulchra Chisternon undatum Baena arenosa Denazinemys nodosa

References

1. Sullivan, R.M.; Jasinski, S.E.; Lucas, S.G. (2013). "Re-Assessment of Late Campanian (Kirtlandian) Turtles from the Upper Cretaceous Fruitland and Kirtland Formations, San Juan Basin, New Mexico, USA" (PDF). In Brinkman, D.B.; et al. (eds.). Morphology and Evolution of Turtles. Vertebrate Paleobiology and Paleoanthropology. pp. 337–339. doi:10.1007/978-94-007-4309-0_20. ISBN   978-94-007-4308-3. Archived from the original (PDF) on 2014-02-28. Retrieved 2014-02-19.
2. Spicher, G.E.; Sertich, J.J.; Girard, L.C.; Joyce, W.G.; Lyson, T.R.; Rollot, Y. (2023). "A description of a Denazinemys nodosa specimen (Testudinata, Baenidae) from the Late Cretaceous Kaiparowits Formation of southern Utah". Fossil Record. 26 (2): 151–170. Bibcode:2023FossR..26..151S. doi: 10.3897/fr.26.102520 .
3. Lehman, T. M.; Tomlinson, S. L.; Shiller, T. A.; Wick, S. L. (2025). "Turtles of the Aguja and Javelina Formations, Upper Cretaceous (Campanian – Maastrichtian), West Texas". Cretaceous Research. 174. 106145. Bibcode:2025CrRes.17406145L. doi:10.1016/j.cretres.2025.106145.

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