Paleobiological inferences for the Antarctic dinosaur Antarctopelta oliveroi (Ornithischia: Ankylosauria) based on bone histology of the holotype

CERDA, IGNACIO A.; GASPARINI, ZULMA; CORIA, RODOLFO A.; SALGADO, LEONARDO; REGUERO, MARCELO; PONCE, DENIS; GONZÁLEZ, ROMINA; JANELLO, MARCOS ; MOLY, JUAN JOSÉ

CRETACEOUS RESEARCH (PRINT)

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Año: 2019 vol. 103 p. 1 - 16

0195-6671

A detailed histological study of Antarctopelta oliveroi, from the Upper Cretaceous of Antarctica, is performed, in order to increase the knowledge on the ankylosaur bone histology and its taxonomical and paleobiological implications. The main objectives of this contribution are: to infer the ontogenetic stage of the holotype of Antarctopelta oliveroi; to evaluate the degree of interelemental histological variation; to compare with the histology of other ankylosaurs; to provide information about the phylogenetic affinities of Antarctopelta using dermal armor histology; and to evaluate how the growth of Antarctopelta could be affected by the strong seasonality, which is inferred from the high paleolatitude where this ankylosaur lived. Several postcranial elements from the holotype specimen (e.g. osteoderms, appendicular bones, dorsal ribs, ossified tendons) were included in the sample. The bone histology reveals that the specimen was sexually mature but possibly still growing at time of death. Primary cortical bone, mostly composed of fibrolamellar bone tissue interrupted with growth marks, reveals cyclical growth strategy as reported for other non-avian dinosaurs, including ankylosaurs. The number of growth marks preserved in the cortical bone is, however, strongly variable among different kind of elements. Dermal armor histology supports nodosaurid affinities of Antarctopelta. Histological data reveals an osseous pathology in the individual. The bone histology of Antarctopelta does not reveal differences in growth strategy with low latitude relatives, like other polar dinosaurs from the Southern Hemisphere. Therefore, no evident physiological modifications appears to be necessary for the establishment of ankylosaurs and other non-avian dinosaurs in high latitudes (>60° S) regions.