Miguel P. Marx (1,2,3), Octávio Mateus (2,3), Michael J. Polcyn (1), Anne S. Schulp (4,5), A. Olímpio Gonçalves (6), Louis L. Jacobs (1)
PLOS ONE, 16, Issue 8, August 2021. DOI: 10.1371/journal.pone.0255773

Abstract

We report a new specimen of the plesiosaur Cardiocorax mukulu that includes the most complete plesiosaur skull from sub-Saharan Africa. The well-preserved three-dimensional nature of the skull offers rare insight into the cranial anatomy of elasmosaurid plesiosaurians. The new specimen of Cardiocorax mukulu was recovered from Bentiaba, Namibe Province in Angola, approximately three meters above the holotype. The new specimen also includes an atlas-axis complex, seventeen postaxial cervical vertebrae, partial ribs, a femur, and limb elements. It is identified as Cardiocorax mukulu based on an apomorphy shared with the holotype where the cervical neural spine is approximately as long anteroposteriorly as the centrum and exhibits a sinusoidal anterior margin. The new specimen is nearly identical to the holotype and previously referred material in all other aspects. Cardiocorax mukulu is returned in an early-branching or intermediate position in Elasmosauridae in four out of the six of our phylogenetic analyses. Cardiocorax mukulu lacks the elongated cervical vertebrae that is characteristic of the extremely long-necked elasmosaurines, and the broad skull with and a high number of maxillary teeth (28–40) which is characteristic of Aristonectinae. Currently, the most parsimonious explanation concerning elasmosaurid evolutionary relationships, is that Cardiocorax mukulu represents an older lineage of elasmosaurids in the Maastrichtian.

How Our Software Was Used

Dragonfly was used to take measurements of the cranium, mandible, and vertebrae of a specimen.

Author Affiliation

(1) Huffington Department of Earth Sciences, ISEM at Southern Methodist University, Dallas, Texas, United States of America.
(2) GeoBioTec + Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal.
(3) Museu da Lourinhã, Lourinhã, Portugal.
(4) Naturalis Biodiversity Center, Leiden, The Netherlands.
(5) Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands.
(6) Departamento de Geologia, Faculdade de Ciências, Universidade Agostinho Neto, Luanda, Angola.