The evolution of mammal-like crocodyliforms in the Cretaceous Period of Gondwana.
TANZANIA; ANIMAL classification; ANIMAL diversity; ANIMAL species; CRETACEOUS paleoecology; EVOLUTION (Biology); FOSSIL crocodylidae; TAXONOMY
Fossil crocodyliforms discovered in recent years have revealed a level of morphological and ecological diversity not exhibited by extant members of the group. This diversity is particularly notable among taxa of the Cretaceous Period (144–65 million years ago) recovered from former Gondwanan landmasses. Here we report the discovery of a new species of Cretaceous notosuchian crocodyliform from the Rukwa Rift Basin of southwestern Tanzania. This small-bodied form deviates significantly from more typical crocodyliform craniodental morphologies, having a short, broad skull, robust lower jaw, and a dentition with relatively few teeth that nonetheless show marked heterodonty. The presence of morphologically complex, complementary upper and lower molariform teeth suggests a degree of crown–crown contact during jaw adduction that is unmatched among known crocodyliforms, paralleling the level of occlusal complexity seen in mammals and their extinct relatives. The presence of another small-bodied mammal-like crocodyliform in the Cretaceous of Gondwana indicates that notosuchians probably filled niches and inhabited ecomorphospace that were otherwise occupied by mammals on northern continents. [ABSTRACT FROM AUTHOR]
O'Connor Patrick M; Sertich Joseph J W; Stevens Nancy J; Roberts Eric M; Gottfried Michael D; Hieronymus Tobin L; Jinnah Zubair A; Ridgely Ryan; Ngasala Sifa E; Temba Jesuit
Nature
2010
2010-08-05
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1038/nature09061" target="_blank" rel="noreferrer noopener">10.1038/nature09061</a>
Palaeontological evidence for an Oligocene divergence between Old World monkeys and apes.
AFRICA; APES; BIOTIC communities; CERCOPITHECIDAE; OLIGOCENE Epoch; PALEONTOLOGY; TANZANIA
Apes and Old World monkeys are prominent components of modern African and Asian ecosystems, yet the earliest phases of their evolutionary history have remained largely undocumented. The absence of crown catarrhine fossils older than ∼20 million years (Myr) has stood in stark contrast to molecular divergence estimates of ∼25-30 Myr for the split between Cercopithecoidea (Old World monkeys) and Hominoidea (apes), implying long ghost lineages for both clades. Here we describe the oldest known fossil 'ape', represented by a partial mandible preserving dental features that place it with 'nyanzapithecine' stem hominoids. Additionally, we report the oldest stem member of the Old World monkey clade, represented by a lower third molar. Both specimens were recovered from a precisely dated 25.2-Myr-old stratum in the Rukwa Rift, a segment of the western branch of the East African Rift in Tanzania. These finds extend the fossil record of apes and Old World monkeys well into the Oligocene epoch of Africa, suggesting a possible link between diversification of crown catarrhines and changes in the African landscape brought about by previously unrecognized tectonic activity in the East African rift system. [ABSTRACT FROM AUTHOR]
Stevens Nancy J; Seiffert Erik R; O'Connor Patrick M; Roberts Eric M; Schmitz Mark D; Krause Cornelia; Gorscak Eric; Ngasala Sifa; Hieronymus Tobin L; Temu Joseph
Nature
2013
2013-05-30
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1038/nature12161" target="_blank" rel="noreferrer noopener">10.1038/nature12161</a>