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Huttenlocker A.K.,University of Washington | Sidor C.A.,University of Washington | Smith R.M.H.,Iziko South African Museum
Journal of Vertebrate Paleontology | Year: 2011

The anatomy of a new subadult specimen of eutherocephalian therapsid, attributed to Promoschorhynchus cf. P. platyrhinus, is described from lowermost Triassic Lystrosaurus Assemblage Zone strata in the main Karoo Basin of South Africa. The specimen preserves information previously unknown in the genus, including details of the posterior region of the skull and intertemporal region, and a partial (though disarticulated) postcranial skeleton. A cladistic analysis of 32 therapsid taxa, including 24 Permo-Triassic therocephalian genera, and 121 craniodental and postcranial characters supports the specimen's placement within the Permian akidnognathid genus Promoschorhynchus (making it the youngest documented occurrence of this taxon) within a monophyletic Therocephalia. Inclusion of new postcranial characters strengthens support of the therocephalian clade. The new record of Promoschorhynchus offers insights into the diversity of eutheriodonts across the Permo-Triassic boundary (PTB) in the Karoo Basin. In contrast to cynodonts, therocephalians exhibited decreased rates of cladogenesis across the PTB, with several Triassic lineages having roots in the Late Permian rather than representing earliest Triassic radiations. © 2011 by the Society of Vertebrate Paleontology. Source


Buffington M.L.,U.S. Department of Agriculture | Brady S.G.,Smithsonian Institution | Morita S.I.,Smithsonian Institution | Morita S.I.,North Carolina State University | And 2 more authors.
Systematic Entomology | Year: 2012

We examine the phylogenetic relationships of Figitidae and discuss host use within this group in light of our own and previously published divergence time data. Our results suggest Figitidae, as currently defined, is not monophyletic. Furthermore, Mikeiinae and Pycnostigminae are sister-groups, nested adjacent to Thrasorinae, Plectocynipinae and Euceroptrinae. The recovery of Pycnostigminae as sister-group to Mikeiinae suggests two major patterns of evolution: (i) early Figitidae lineages demonstrate a Gondawanan origin (Plectocynipinae: Neotropical; Mikeiinae and Thrasorinae: Australia; Pycnostigminae: Africa); and (ii) based on host records for Mikeiinae, Thrasorinae and Plectocynipinae, Pycnostigminae are predicted to be parasitic on gall-inducing Hymenoptera. The phylogenetic position of Parnips (Parnipinae) was unstable, and various analyses were conducted to determine the impact of this uncertainty on both the recovery of other clades and inferred divergence times; when Parnips was excluded from the total evidence analysis, Cynipidae was found to be sister-group to [Euceroptrinae + (Plectocynipinae (Thrasorinae + (Mikeiinae + Pycnostigminae)))], with low support. Divergence dating analyses using BEAST indicate the stem-group node of Figitidae to be c. 126 Ma; the dipteran parasitoids (Eucoilinae and Figitinae), were estimated to have a median age of 80 and 88 Ma, respectively; the neuropteran parasitoids (Anacharitinae), were estimated to have a median age of 97 Ma; sternorrhynchan hyperparasitoids (Charipinae), were estimated to have a median age of 110 Ma; the Hymenoptera-parasitic subfamilies (Euceroptinae, Plectocynipinae, Trasorinae, Mikeiinae, Pycnostigminae, and Parnipinae), ranged in median ages from 48 to 108 Ma. Rapid radiation of Eucoilinae subclades appears chronologically synchronized with the origin of their hosts, Schizophora (Diptera). Overall, the exclusion of Parnips from the BEAST analysis did not result in significant changes to divergence estimates. Finally, though sparsely represented in the analysis, our data suggest Cynipidae have a median age of 54 Ma, which is somewhat older than the age of Quercus spp (30-50 Ma), their most common host. © 2012. Source


Matthews T.,Iziko South African Museum | Stynder D.D.,University of Cape Town
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2011

Subsequent to the initial description of two Aethomys species (Aethomys adamanticola and Aethomys modernis) at the Early Pliocene site of Langebaanweg (LBW), an increase in sample size led to the secure identification of a third, as yet, undescribed species. In addition to this new species, three morphs of existing species, or possibly three new species, were also recognized. Geometric morphometrics was used to explore the relationship of fossil species and morphs with extant Aethomys species, and to assess the intra and inter-specific variation in the size and shape of modern, as well as the LBW, Aethomys specimens. Geometric morphometrics indicates a marked similarity in the upper first molar (M1) shape between all the analyzed species, extant and extinct, and suggests the persistence, over a significant period of time, of a prototype Aethomys M1 shape. The relative warp analyses indicate some overlap in shape between the two modern species, Aethomys chrysophilus and Aethomys namaquensis, as well as some inter-specific variation. These two species differ significantly from one another in terms of size. Variability in terms of size and to a minor extent, shape, was also evident in the fossil Aethomys, and it was concluded that the various fossil morphs investigated did not represent new species, or intra-specific sexual dimorphism, but rather, intra-specific variability in size and shape. Interestingly, the newly-identified LBW Aethomys species, which is similar in appearance to the extant east African Aethomys kaiseri, also showed a similarity in shape and size to A. adamanticola. These results indicate that geometric morphometrics has limitations when differentiating between morphologically similar species. The presence of Aethomys in Namibia at around 10.5 to 9.5Ma, the degree of speciation of Aethomys at LBW, and the similarity of the LBW fossil species to the modern ones (including an East African species), provides good evidence for a southern African origin for modern Aethomys. © 2011 Elsevier B.V. Source


McLeish M.J.,Stellenbosch University | McLeish M.J.,South African National Biodiversity Institute | Van Noort S.,Iziko South African Museum | Tolley K.A.,South African National Biodiversity Institute
Molecular Ecology | Year: 2010

Ecological processes are manifest in the evolution and form of phenotype diversity. The great abundance of parasitoid species has led to speculation whether rates of speciation and extinction are dependent on parasitoid diversity. If these factors are mutually exclusive, species diversity should fluctuate instead of remaining relatively constant over time. It is not known whether radiations constrained by coevolutionary interactions conform to density-dependent diversification processes. Here we test the prediction that parasitoid fig wasp diversification responds to changes in ecological opportunity and density-independent processes. A phylogenetic approach is used to estimate relative divergence times and infer diversification rate changes using γ-statistics. Monte Carlo constant rates tests that accommodate incomplete sampling could not reject constant rates diversification. Parasitoid fig wasp diversification is consistent with a more complex explanation than density-dependent cladogenesis. The results suggest contemporary African parasitoid fig wasp diversity remains a legacy of an ancient ecological opportunity facilitated by fig tree diversification following the breakup of Pan-African forests and evolution of the savanna biome over the last 55 Ma and the more recent aridification of the African continent in the last 5 Ma. These results imply that amplified phenotypic differentiation of specialist insects coevolving with plants is coupled to evolutionarily infrequent changes in ecological opportunity. © 2010 Blackwell Publishing Ltd. Source


Three taxa of desmoceratoid ammonites are recognized in the Lower Albian of northern KwaZulu-Natal, all of them previously known only from Madagascar: Moretella sp., Beudanticeras komihevitraense Collignon, 1950, and Aioloceras besairiei (Collignon, 1949). Madagascan type and figured material, much of it difficult to interpret from the original figures is re-illustrated, and the intraspecific variation and dimorphism in Moretella and Aioloceras are documented. Source

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