In:
Palaeontology, Wiley, Vol. 59, No. 1 ( 2016-01), p. 155-169
Abstract:
The M iddle J urassic was a key interval of mammalian evolutionary history that witnessed the diversification of the therian stem group. G reat B ritain has yielded a significant record of mammalian fossils from this interval, represented by numerous isolated jaws and teeth from the B athonian of O xfordshire and the I sle of S kye. This record captures a key period in early cladotherian evolution, with amphitheriids, peramurans and ‘stem zatherians’ displaying intermediate talonid morphologies that document the evolutionary assembly of tribosphenic molars. We present a mandible with near‐complete dentition from the late B athonian ( c . 167.4–166.5 Ma) K ilmaluag F ormation, near E lgol, S kye, representing the amphitheriid P alaeoxonodon ooliticus , previously known only from isolated teeth. The specimen sheds new light on the taxonomic diversity of B ritish M iddle J urassic stem therians, as the morphological variation within the preserved tooth row encompasses that previously ascribed to three distinct species within two genera: P alaeoxonodon ooliticus , P . freemani and K ennetheridium leesi . Thus, both P . freemani and K . leesi are subjective junior synonyms of P . ooliticus . The dental formula of P . ooliticus (i4:c1:p5:m5) is intermediate between the primitively larger postcanine count (p5:m6–7) of A mphitherium and the reduced number in peramurans and tribosphenidans (p5:m3). Phylogenetic analyses of P . ooliticus generally confirm a close affinity with A mphitherium , but highlight the lack of strong empirical support for hypothesized patterns of divergences among early cladotherians.
Type of Medium:
Online Resource
ISSN:
0031-0239
,
1475-4983
DOI:
10.1111/pala.2016.59.issue-1
Language:
English
Publisher:
Wiley
Publication Date:
2016
detail.hit.zdb_id:
2034710-8
SSG:
13
Bookmarklink