First gut contents in a Cretaceous sea turtle

Abstract

Modern sea turtles utilize a variety of feeding strategies ranging from herbivory to omnivory. In contrast, the diets of fossil sea turtles are poorly known. This study reports the first direct evidence: inoceramid bivalve shell pieces (encased in phosphatic material) preserved within the body cavities of several small protostegid turtles (cf. Notochelone ) from the Lower Cretaceous of Australia. The shell fragments are densely packed and approximately 5–20 mm across. Identical shell accumulations have been found within coprolite masses from the same deposits; these are of a correct size to have originated from Notochelone , and indicate that benthic molluscs were regular food items. The thin, flexible inoceramid shells (composed of organic material integrated into a prismatic calcite framework) appear to have been bitten into segments and ingested, presumably in conjunction with visceral/mantle tissues and encrusting organisms. Although protostegids have been elsewhere interpreted as potential molluscivores, their primitive limb morphology is thought to have limited them to surface feeding. However, the evidence here that at least some forms were able to utilize benthic invertebrate prey indicates that, like modern sea turtles, protostegids probably exhibited a much broader range of feeding habits.

The Evolution of Marine Reptiles

“…One study shows that Notochelone of the Cretaceous fed on bivalve mollusks (Kear 2006). It is important to note that the true sea turtles (Chelonioidea) were not the only turtles that became marine.…”

Coprolite of a durophagous carnivore from the Upper Cretaceous Godula Beds, Outer Western Carpathians, Poland

“…Inoceramid shells in the coprolite spec i men ZPAL Tf.6 un der a ste reo scope mi cro scope A -weath ered shell ex posed on the spec i men sur face; B -small shell frag ment in side the spec i men depths of sev eral hun dred of metres be low the wa ter sur face in full ma rine eco sys tems, even reach ing 1200 me ters of depth (Spotila, 2004). How ever, the protostegid tur tle stom ach contents de scribed by Kear (2006) come from a shal low sea en viron ment (<100 m depth). Al though both fishes and rep tiles could po ten tially pro duce this coprolite based on the mor phol ogy of the spec i men and its con tent, a fish seems a more prob a ble producer.…”

“…comm., 2013). More over, inoceramid shells were de scribed from stomach con tents and cop ro lites of sea tur tles from the Up per Albian )Toolebuc For ma tion, Aus tra lia (Kear, 2006). Mod ern sea tur tles may feed on nektonic and ben thic fauna in Fig.…”

Inferred vertebrate bite marks on an Early Cretaceous unionoid bivalve from Lightning Ridge, New South Wales, Australia

“…Kauffman & Kesling 1960, Kauffman 1972 and ingested remains preserved as gut contents (e.g. McHenry et al 2005, Kear 2006a or coprolites/regurgitated masses (e.g. Speden 1971, Hattin 1996, Kear 2006a).…”