Browsing by Author "Dyke, Gareth."
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Item The fossil galliform bird Paraortygoides from the Lower Eocene of the United Kingdom. American Museum novitates ; no. 3360(New York, NY : American Museum of Natural History, 2002) Dyke, Gareth.; Gulas, Bonnie E.; Vincent, Steve.A new fossil species assigned to the galliform genus Paraortygoides Mayr is described from the Lower Eocene (Ypresian Stage) London Clay Formation of the United Kingdom. Paraortygoides radagasti, n. sp., is referred to the genus on the basis of comparisons with other specimens from the Middle Eocene deposit of Messel (Hessen, Germany). Because of the three-dimensional preservation of this fossil material, P. radagasti contributes new information pertaining to the morphology of the genus Paraortygoides, in particular with regard to the thoracic vertebrae, tarsometatarsus, and toes. This genus, for example, is distinguished from other currently known fossil and extant galliform birds by the presence of deep pneumatic excavations in the lateral sides of the thoracic vertebrae. The results of a preliminary phylogenetic analysis suggest that Paraortygoides is basal within Galliformes (as already proposed by Mayr (2000)); monophyly of the order is supported with Megapodiidae as the basal sister taxon with respect to the Cracidae and Phasianidae. Paraortygoides radagasti is one of the oldest galliform birds described to date; its age and degree of preservation provide a reliable early phylogenetic constraint for the divergence of a basal clade within the order Galliformes.Item The fossil waterfowl (Aves, Anseriformes) from the Eocene of England. American Museum novitates ; no. 3354(New York, NY : American Museum of Natural History, 2001) Dyke, Gareth.The taxonomy and phylogenetic positions of the fossil waterfowl (Aves: Anseriformes) described from the Eocene of England are reviewed. Although a total of six species within five genera have been described, only the phylogenetic positions of the two taxa Anatalavis oxfordi Olson and Headonornis (Lydekker) can be hypothesized with confidence within the order Anseriformes. Anatalavis oxfordi is considered to be the sister taxon to a clade comprising another fossil waterfowl, Presbyornis Wetmore, and the extant true ducks, Anatidae, whereas Headonornis may be congeneric with Presbyornis. Fossil material referred to the genera Palaeopapia Harrison and Walker and Paracygnopterus Harrison and Walker is considered Aves incertae sedis.Item A medium-sized robust-necked azhdarchid pterosaur (Pterodactyloidea, Azhdarchidae) from the Maastrichtian of Pui (Hațeg Basin, Transylvania, Romania). (American Museum novitates, no. 3827)(American Museum of Natural History., 2015-03-17) Vremir, Mátyás.; Witton, Mark P., 1984-; Naish, Darren.; Dyke, Gareth.; Brusatte, Stephen.; Norell, Mark.; Totoianu, Radu.We describe a pterosaurian cervical vertebra collected from Maastrichtian sediments at the Pui locality in the Hațeg Basin, Romania. This specimen, a medium-sized, robust fourth cervical, is distinctive in morphology and represents a new, as yet unrecognized, azhdarchid pterosaur size class within the Haţeg Island fauna: it most likely belongs to a new taxon which we opt not to name here. The vertebra is referred to Azhdarchidae based on clearly preserved diagnostic features characteristic of this group and differs in proportions and anatomical details from the recently named azhdarchid Eurazhdarcho langendorfensis Vremir et al., 2013a, from the Sebeș region of the Transylvanian basin. We take issue with claims that all Maastrichtian Romanian azhdarchids (and other penecontemporaneous azhdarchids and azhdarchoids) should be uncritically assumed to be synonymous: it ignores anatomical characters that allow the specimens concerned to be differentiated and is based on an erroneous "one stratum, one species" philosophy contradicted by empirical data from other azhdarchoid assemblages. It has been suggested that the absence of small to medium-sized pterosaurs in Upper Cretaceous sediments is indicative of an evolutionary trend. However, evidence from the Hațeg Island fauna may indicate instead that smaller-sized pterosaurs were indeed present in this interval but remain underrepresented due to rare preservation and collection.Item New records of fossil 'waterbirds' from the Miocene of Kenya ; American Museum novitates, no. 3610(New York, NY : American Museum of Natural History, 2008) Dyke, Gareth.; Walker, Cyril Alexander.;We present a number of new fossil records of "waterbirds" (encompassing several of thetraditional living orders of birds) from three important Miocene deposits in western Kenya. These sites surround Lake Victoria--the Ngorora Formation and sediments at Maboko and Rusinga Islands (Kula Formation)--are well-known hominoid localities, and have yielded a diverse assemblage of contemporary fossil mammals. Previously identified avians from this area include amarabou stork (Leptoptilos sp.), the fossil flamingo Leakeyornis aethiopicus, as well as a number of additional unidentified phoenicopterid (flamingo) remains. We add records of an anhinga (Anhinga cf. pannonica), two storks (Ciconia minor, C. cf. ciconia/nigra), a night heron (Nycticorax cf. nycticorax) and a threskyornithid (the group that includes the ibises and spoonbills) to the known diversity of Kenyan Miocene waterbirds. We also illustrate, for the first time, the holotype and paratype material of the Kenyan Miocene flamingo Leakeyornis aethiopicus. Comparisons with other known sites of this age across northern Africa, the Mediterranean and northern Pakistan suggest that Miocene waterbird faunas in this region were very similar in their compositions. While Anhinga pannonica, Ciconia minor, and Ciconia ciconia are documented from other Miocene sites across the region, the osteologically distinct fossil flamingo Leakeyornis appears to have been restricted to East Africa. All the avian groups recorded from these Kenyan Miocene sites represent extant genera, in contrast to the described fossil mammals. As has been widely reported from other African sites of this age, fossil birds thus represent a valid mechanism for building hypotheses about palaeoenvironments.