It only took one 13-million-year-old bone for two paleontologists to reconstruct the dramatic encounter pictured above. That bone is a tibia, or lower leg bone, from an extinct ground sloth (not a giant ground sloth, just a 170 pound medium-sized one). The tibia has 46 tooth marks on it, made by the extinct caiman (a close relative of alligators) Purussaurus.
Read the paper by Pujos and Salas-Gismondi to see how, through a detailed taphonomic analysis of a single bone, they were able to infer not only what animal did the biting, but also how old it was. Unresolved: whether the caiman got the whole sloth or just the leg.
Pujos F, Salas-Gismondi R. 2020 Predation of the giant Miocene caiman Purussaurus on a mylodontid ground sloth in the wetlands of proto-Amazonia. Biology Letters 16: 20200239. http://dx.doi.org/10.1098/rsbl.2020.0239
Featured image: Detail of Figure 2 from Pujos and Salas-Gismondi. Artwork by Jorge A. González.
Ashfall Fossil Beds State Historical Park in Nebraska has paid internships available. Ashfall preserves the articulated skeletons of 12-million year old rhinoceros, horses, camels, and deer who died after a volcanic eruption.
Several summer internships are available for field studies in vertebrate paleontology. With preference to geology or biology students, the positions are open to all students with a genuine interest in, and knowledge of vertebrate paleontology, especially those aspiring to further their experience outside of the classroom. Duties include excavation, sorting of micro-vertebrate fossils, prep lab tasks, interpretive duties and other park support tasks.
36-38 hour workweek. $11.50 per hour.
* Three internships will be offered for May 24 to August 10.
* Two internships will be offered for June 20 to September 15.
* One internship will be offered for September 3 to October 20.
Deadline: Applications will be accepted until all positions have been filled, but no later than April 1st. Therefore, advantage to early applicants. Contact the Superintendent at Ashfall for more information.