18 research outputs found

    The interrelationships of the Giraffidae

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    Dead ossicones, and other characters describing Palaeotraginae (Giraffidae; Mammalia) based on new material from Gansu, Central China

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    While the identity and validity of the extant families of ruminants are undoubted, there are significant problems with the determination of the interrelationships among the families, notably within the families of the Pecora, or horned ruminants. The morphological features used to construct ruminant phylogeny have been a source of controversy: many features used over the past century have been shown to be highly homoplastic and related to functional similarities. Ruminants evolved in the context of the later Cenozoic climatic changes, and many lineages adopted functional morphological adaptations related to feeding on more abrasive diets (resulting in the parallel evolution of a greater extent of loph development in the molars and, in some lineages, hypsodonty) and locomotion in open habitats (resulting in the parallel evolution of fused metapodials and reduction and/or loss of lateral digits). The fact that the molecular phylogeny shows a very different pattern from the currently accepted morphological one is of particular cause for concern, especially as molecular data are of no use for understanding the relationships of extinct lineages. Here we review the morphological data used in ruminant phylogenetics, and show even many of the less obviously functional features (e.g., number and position of the lacrimal orifices) are subject to homoplasy and variation, especially when fossil taxa are included. In addition, many morphological features treated as independent traits in phylogenetics are correlated (e.g., cranial morphology associated with hypsodonty). Some potentially reliable features are identified, but these do not help to sort out relationships within the Pecora. We advocate for the investigation into better morphological features, possibly derived from basicranial and ear region characters (although these features are not without their own issues of homoplasy), and for caution in character consideration in performing phylogenetic analyses

    A new species of Euprox (Cervidae, Artiodactyla) from the upper Miocene of the Linxia Basin, Gansu Province, China, with interpretation of its paleoenvironment

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    Hou, Sukuan (2015): A new species of Euprox (Cervidae, Artiodactyla) from the upper Miocene of the Linxia Basin, Gansu Province, China, with interpretation of its paleoenvironment. Zootaxa 3911 (1): 43-62, DOI: 10.11646/zootaxa.3911.1.

    A new species of Chleuastochoerus (Artiodactyla: Suidae) from the Linxia Basin, Gansu Province, China

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    Hou, Sukuan, Deng, Tao (2014): A new species of Chleuastochoerus (Artiodactyla: Suidae) from the Linxia Basin, Gansu Province, China. Zootaxa 3872 (5): 401-439, DOI: 10.11646/zootaxa.3872.5.

    A new method of tooth mesowear and a test of it on domestic goats. Annales Zoologici Fennici 51

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    Mesowear III is a new form of mesowear that uses separately the mesial and distal surfaces of enamel band 2 of the upper second molar to differentiate between a browsing and a grazing diet. The enamel band of browsers is flat and planar, in grazers it contains gouges and sub-facets which eventually become round. Mesowear III scores these shapes on a scale 1-4; score 1 represents the typical browser and score 4 represents a typical grazer. Differences in diet can also be studied by observing the junction between the mesial and distal side of the enamel band (j point); the j point is sharper and well defined in browsers, while it is rounder or non-existent in grazers. Wild browsers, grazers, and mixed feeders separate well using mesowear III. The wild taxa data were similar to mesowear III of experimental goats that were fed a controlled grazing or browsing diet (species of plants known). In addition, the browsing versus the grazing goat mesowear III signal becomes more distinct from each other by 40 days of feeding. Mesowear III so far gives a finer signal than previous mesowear (I and II)

    Comparisons of Schansitherium tafeli with Samotherium boissieri (Giraffidae, Mammalia) from the Late Miocene of Gansu Province, China.

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    We are describing and figuring for the first time skulls of Schansitherium tafeli, which are abundant in the Gansu area of China from the Late Miocene. They were animals about the size of Samotherium with shorter necks that had two pairs of ossicones that merge at the base, which is unlike Samotherium. The anterior ossicones consist of anterior lineations, which may represent growth lines. They were likely mixed feeders similar to Samotherium. Schansitherium is tentatively placed in a very close position to Samotherium. Samotherium and Schansitherium represent a pair of morphologically very similar species that likely coexisted similarly to pairs of modern species, where the main difference is in the ossicones. Pairs of ruminants in Africa, for example, exist today that differ mostly in their horn shape but otherwise are similar in size, shape, and diet. The absence of Schansitherium from Europe is interesting, however, as Samotherium is found in both locations. While is it challenging to interpret neck length and ossicone shape in terms of function in combat, we offer our hypothesis as to how the two species differed in their fighting techniques

    Comment on "Sexual selection promotes giraffoid head-neck evolution and ecological adaptation"

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