Trace fossils on dinosaur bones reveal ecosystem dynamics along the coast of eastern North America during the latest Cretaceous

Abstract

Direct evidence of paleoecological processes is often rare when the fossil record is poor, as in the case of the Cretaceous of eastern North America. Here, I describe a femur and partial tibia shaft assignable to theropods from two Late Cretaceous sites in New Jersey. The former, identifiable as the femur of a large ornithomimosaur, bears several scores interpreted as shark feeding traces. The tibia shaft has punctures and flaked bone from the bites of mid-sized crocodyliforms, the first documented occurrence of crocodyliform traces on dinosaur bone from the Maastrichtian of the Atlantic Coastal Plain. The surface of the partial tibia is also littered with indentations interpreted as the traces of invertebrates, revealing a microcosm of biological interaction on the coastal seafloor of the Cretaceous Atlantic Ocean. Massive crocodyliforms, such as Deinosuchus rugosus and the slightly smaller Deltasuchus motherali, maintained the role of terrestrial vertebrate taphonomic process drivers in eastern North America during the Cretaceous. The report of crocodyliform bite marks on the ornithomimosaur tibia shaft in this manuscript reinforces the importance of the role of crocodyliforms in the modification of terrestrial vertebrate remains during the Cretaceous in North America. The preserved invertebrate traces add to the sparse record of the presence of barnacles and other marine invertebrates on dinosaur bone, and the evidence of shark feeding on the ornithomimosaur femur support the “bloat-and-float” model of terrestrial vertebrate fossil deposition in marine deposits from the Cretaceous of eastern North America.

The integument of pelagic crocodylomorphs (Thalattosuchia: Metriorhynchidae)

“…The potential traces of epizoa reported herein would be the first documentation of coevolution with Mesozoic marine reptiles. Zangerl (1948) reported on bryozoans and a questionable barnacle on a Cretaceous turtle, but likely a freshwater form, hence epibenthic on allochthonous bones (see also Brownstein, 2018). Particularly for the Late Jurassic Solnhofen Archipelago, no match with known invertebrates could be recognized, implying a new ecological component (Figure 28).…”

Ghosts of the Holobiont: Borings on a Miocene Turtle Carapace from the Pisco Formation (Peru) as Witnesses of Ancient Symbiosis

“…Overlooked until recently, the modifications induced by the attachment of acorn barnacles (Cirripedia: Balanomorpha) on submerged bones are beginning to receive some attention by taphonomists, both in the field of forensics [1,2] and in that of palaeontology [3,4]. In fact, barnacles are known as encrusters of defleshed bones in extant as well as fossil marine settings [1,2,[4][5][6][7][8][9][10][11].…”