Arvinachelys: another pig-nose turtle

Arvinachelys goldeni (Lively 2015; Late Cretaceous; UMNH VP 21151; 60cm in length; Figs. 1, 2) was promoted as a unique pig-nose turtle, having twin narial openings. That trait is now shared with Kallokibotion (Nopsca 1923; Pérez-García and Vlad Codrea 2018; Fig. 2), which we looked at earlier here. This is a near-basal turtle nesting near baenids and before any extant taxa (crown group) among the hard-shell turtles.

Arvinachelys is not closely related
to the living pig-nose turtle, Carettochelys.

Lively 2015
fused many of the skull bones together in his µCT scan (Fig. 1). I was able to trace outlines for several fused elements. I also relabeled the squamosal as the supratemporal. Lively did not identify the top half of the premaxilla, separated from the bottom half in the adult skull. Though rare, such splits do occur in certain other turtles, Lively did not identify the bottom half of the jugal, recolored here.

Figure 1. Arvinachelys as originally figured, then with several fused bones segregated with colors.

Figure 1. Arvinachelys as originally figured, then with several fused bones segregated with colors.

Figure 3. Kallokibotion compared to Meiolania.

Figure 3. Kallokibotion (at right) compared to Meiolania. The former also has divided narial openings and precedes Arniachelys phylogenetically.

Journalist call this turtle’s twin nares ‘bizarre’ and ‘weird’, even though basal turtles, like Proganochelys share this trait. When you think about it, there are several turtles that are much more weird than Arvinachelys. Superlatives, whether warranted or not, seem to drive paleo publicity.

Lively J 2015. A new species of baenid turtle from the Kaiparowits Formation (Upper Cretaceous: Campanian) of southern Utah. Journal of Vertebrate Paleontology. doi:10.1080/02724634.2015.1009084
Pérez-García A and Vlad Codrea 2018. New insights on the anatomy and systematics of Kallokibotion Nopcsa, 1923, the enigmatic uppermost Cretaceous basal turtle (stem Testudines) from Transylvania. Zoological Journal of the Linnean Society. 182(2):419–443. doi:10.1093/zoolinnean/zlx037.


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