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Vesmír č. 10
Vesmír č. 10
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2. 10. 2017
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Čumáček a varlata

Snout and testes – what is a morphological support for afrotherian mammals? by Jan Robovský.

Afrotheria comprises a newly recognized clade of mammals with strong molecular evidence for its monophyly. Afrotheria including elephants, sea cows, hyraxes, aardvarks, sengis, tenrecs and golden moles has been believed to be without any morphological support. Recent analyses have shown that Afrotheria shares several morphological characters, e.g. testicondy (absence of testicular descent), snout musculature, a large allantois sac divided into four intercommunicating lobes by two pair of septal folds, an increase in the number of thoracolumbar vertebrae and delayed dental eruption. Seiffert (2007) identified even 21 morphological characters shared by Afrotheria. This clade is also supported by several chromosomal characters and some reproductive (e.g. slower reproduction, lower number of mammae) and physiological characters (e.g. lower body temperature) are candidates for an additional non-molecular support. Insectivore-like morphology in tenrecs and golden mole is probably a secondary state obtained from the ungulate-like morphology present now or in the past in all other afrotherian mammals including sengis (cf. Zack et al. 2005). Afrotheria need not have an African origin, Africa could be its secondary refuge (Zack et al. 2005).