An accumulation of turtle eggs with embryos from the Campanian (Upper Cretaceous) Judith River Formation of Montana

Abstract

A weathered accumulation of turtle eggs, interpreted as remnants of a single clutch composed of at least 16 turtle eggs (MOR 710) from the Campanian (Upper Cretaceous) Judith River Formation of northcentral Montana, USA, represents a new oospecies Testudoolithus zelenitskyae. This ootaxon is diagnosed by the following unique combination of characters: spherical eggs 34e39 mm in diameter, 660 e760 mm thick eggshell, shell unit height-to-width ratio of 3.15:1e5.5:1, and domed shell units. Estimated egg mass indicates that the egg-laying adult likely possessed a carapace 35.0e54.4 cm in length. Similarities between T. zelenitskyae oosp. nov. and Adocus sp. eggs, along with comparable body size, suggest that this taxon might have produced MOR 710. One egg exhibits abnormal multilayered eggshell, likely resulting from prolonged egg retention by the female turtle. At least five of these eggs, including the multilayered specimen, preserve embryonic remains that demonstrate a late stage of embryonic development. This suggests that death occurred just prior to hatching.

Multiple maternal risk-management adaptations in the loggerhead sea turtle (Caretta caretta) mitigate clutch failure caused by catastrophic storms and predators

“…In conclusion, sea turtles have persisted through several large-scale climate changes, including ocean warming similar in magnitude to the predicted levels of ocean warming over the next 50-100 years [14][15][16][17][18]46,[69][70][71][72][73][74][75][76] . In a cascade of consequences, as ocean warming increases, the number of severe storms will increase.…”

“…Abandonment of clutches after eggs have been deposited is a highly-conserved reproductive adaptation in turtles, originating among the Testudines during the mid-Jurassic period, 174 million years ago [12][13][14][15][16][17][18] . Without extended care of eggs after they are deposited, females must deposit egg clutches on coastal beaches in semitropical-to-tropical regions with temperatures capable of supporting embryo growth and development inside the egg vessel [19][20][21][22] .…”

A gravid fossil turtle from the Early Cretaceous reveals a different egg development strategy to that of extant marine turtles

“…Chicken eggshell and some extant and fossil turtles exhibit dull blue to dark green luminescence (England et al . ; Lawver & Jackson , ) which in the case of fossils indicates minimal alteration of the original composition. In contrast, bright orange to red luminescence indicates the opposite (high alteration and replacement) (Lawver & Jackson , ).…”

“…; Jackson et al . ) from the Lower Cretaceous (Albian) of China, potentially from a terrestrially adapted turtle; (2) T. rigidus (Hirsch ), from several Mesozoic and Cenozoic localities in England, Ethiopia, Spain, France and the USA, also interpreted as laid by terrestrially adapted turtles; (3) T. lordhowensis (Lawver & Jackson ) from the middle to upper Pleistocene of Australia, laid by Meiolania platyceps , a meiolaniform terrestrially adapted turtle; and (4) T. zelenitskyae (Lawver & Jackson ) from the Upper Cretaceous (Campanian) of the USA and Canada, from a turtle potentially related to the genus Adocus , and potentially freshwater‐adapted.…”

A large and unusually thick-shelled turtle egg with embryonic remains from the Upper Cretaceous of China

“…Fossilized turtle embryos are even more uncommon than eggs, but drawing particular interest because they represent one of the most reliable means of determining egg affinity. While there have been published reports of turtle embryos in fossilized eggs [2, [7][8][9][10][11], these remains usually lack anatomical description and thus also lack a specific identification (electronic supplementary material, table S2). Such identification is also possible when eggs are preserved inside a gravid adult, although few such fossil occurrences are known for turtles (i.e.…”