New Extinct Mekosuchine Crocodile from Vanuatu, South Pacific
We describe a new species of crocodile (Reptilia: Crocodyloidea: Mekosuchinae) from a maxilla recovered at the Arapus archaeological site, on the island of Efate, Vanuatu, South Pacific. As with mekosuchine species in New Caledonia and Fiji, Mekosuchus kalpokasi sp. nov. was a small, possibly terrestrial carnivore that is now extinct. The differences between the Efate specimen and previously described species of Mekosuchus warrant recognition of a new species. Based on its association with Efate's earliest known human inhabitants, dating approximately 3000 cal yr B.P., the extinction of M. kalpokasi and other insular mekosuchines may have been anthropogenic. The lack of adequately dated pre-Quaternary and Quaternary vertebrate fossil records from Vanuatu, New Caledonia, and Fiji (as well as other smaller islands) precludes determining the timing and route of dispersal of mekosuchine crocodyloids.Abstract
Map of the South Pacific region showing the locality of mekosuchine fossils including Mekosuchus kalpokasi on Efate, Vanuatu. Reefs are indicated by dotted lines. The approximate expansions of islands and reefs during glacial intervals are illustrated by hachuring (except for those of Solomon Islands and greater New Guinea). The estimates of island size at maximum low sea level stands are taken from bathymetric navigational charts and from Spriggs (1997)
Relationships among living and some extinct crocodyloids based on data from parsimony analyses by a number of authors (A), especially Brochu (1997). The cladogram is not a new analysis of data, rather a generalized diagram to illustrate the various placements of the mekosuchines (B) within the overall Crocodylia. Location number 1 places the mekosuchines outside of Crocodylidae (adapted from Salisbury and Willis 1996:fig. 14; Molnar et al., in press:fig. 13). Location number 2 places the mekosuchines within Crocodylidae (based in part on Brochu, 1997, and pers. comm., December, 2001). Location number 3 places the mekosuchines outside of Alligatoroidea and Crocodyloidea, but its actual placement is vague (inferred from Balouet, 1991:fig. 4)
Mekosuchus kalpokasi holotype, left edentulous maxilla fragment (UF 162724) from Arapus archaeological site, Efate Island, Vanuatu. (A) Lateral (labial) aspect; anterior end to the left. (B) Medial (lingual) aspect; anterior end to the right. (C) Ventral (palatal) aspect; anterior end to the left. The orientation of the maxilla in C is such that it would appear that the palatal fenestra ends at the posterior side of m7, but in reality it ends equal to the anterior edge of this tooth. Scale equals 1 cm