Tavachelydra stevensoni resided in what is now the United States throughout the earliest Paleocene date, in between 66 and 65 million years back– simply after the end-Cretaceous mass termination.

The types comes from Chelydridae, a household of freshwater turtles that consists of a minimum of 7 extinct and 2 living genera.

“The clade of extant chelydrid turtles (Chelydridae) consists of 5 types that are endemic to the New World and whose combined geographical varieties extend from northern South America to southern Canada,” stated Dr. Tyler Lyson from the Denver Museum of Nature & & Science and his associates.

“While not a varied clade, chelydrid turtles are a typical element of the majority of North American freshwater communities.”

“The overall group of chelydrids (i.e., Pan-Chelydridae) is discovered throughout Laurasia, however fossil remains are infamously fragmentary.”

The fossilized carapaces and skulls of 2 Tavachelydra stevensoni people were discovered in the Corral Bluffs Study Area, which lies in El Paso County in south-central Colorado, east of Colorado Springs.

“With a straight carapace length of almost 50 cm, Tavachelydra stevensoni is among the bigger turtles within the early Paleocene (Puercan) of the Denver Basin,” the paleontologists stated.

“Interestingly, 2 pan-chelydrid turtles exist in the early Paleocene of Corral Bluffs, Tavachelydra stevensoni and Denverus middletoni“

“The 2 vary substantially in size, with Tavachelydra stevensoni being at least 4 times bigger than Denverus middletoniwhich likely helped in reducing competitors in between 2 chelydrids with overlapping geographical varieties.”

Little is understood about the paleoenvironment of the single recognized specimen of Denverus middletonihowever the fine- to medium-grained mustard yellow sandstone in which it was discovered was at first translated to represent a channel infill.

The 2 partial Tavachelydra stevensoni skeletons, by contrast, were discovered near one another in a ponded water or distal crevasse splay deposit, so it is sensible to presume that Tavachelydra stevensoni occupied ponded water overbank deposits.

“While absolutely nothing can be stated about the diet plan of Denverus middletoni as its skull is not maintained, Tavachelydra stevensoni had a big skull with broad, flat triturating surface areas a sign of a durophageous diet plan (consuming habits of animals that take in hard-shelled or exoskeleton-bearing organisms, such as corals, shelled mollusks, or crabs),” the scientists stated.

“It for that reason appears possible that Denverus middletoni and Tavachelydra stevensoni inhabited various eco-friendly specific niches, with Tavachelydra stevensoni choosing ponded environments and a durophagous diet plan.”

“Interestingly, turtle types with a durophageous diet plan have a greater survivorship throughout the end-Cretaceous mass termination compared to turtles with a non-durophageous diet plan.”

“In addition to the presumed durophagous dietary choices of Tavachelydra stevensoninumerous of the more typical reptiles explained from Corral Bluffs are likewise analyzed to be durophagous, consisting of the button-toothed crocodylian cf. Wannaganosuchusand the baenid turtles Palatobaena knellerorum Saxochelys gilbertiand Cedrobaena putorius“

“This recommends durophagy was an essential life-history quality for freshwater vertebrates throughout the earliest Paleocene of North America.”

The discovery of Tavachelydra stevensoni is explained in a paper released in the journal Swiss Journal of Palaeontology

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T.R. Lyson et al2025. A brand-new pan-chelydrid turtle, Tavachelydra stevensoni gen. et sp. nov., from the lower Paleocene (early Danian, Puercan) Corral Bluffs Study Area in the Denver Basin, Colorado. Swiss J Palaeontol 144, 46; doi: 10.1186/ s13358-025-00375-4