Sloths
Mostrando 25-29 de 29 artigos, teses e dissertações.
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25. Molecular phylogeny of the extinct ground sloth Mylodon darwinii.
DNA was extracted from the remains of 35 ground sloths from various parts of North and South America. Two specimens of Mylodon darwinii, a species that went extinct at the end of the last glaciation, yielded amplifiable DNA. However, of the total DNA extracted, only approximately 1/1000 originated from the sloth, whereas a substantial part of the remainder w
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26. The evolution of armadillos, anteaters and sloths depicted by nuclear and mitochondrial phylogenies: implications for the status of the enigmatic fossil Eurotamandua.
The mammalian order Xenarthra (armadillos, anteaters and sloths) is one of the four major clades of placentals, but it remains poorly studied from the molecular phylogenetics perspective. We present here a study encompassing most of the order's diversity in order to establish xenarthrans' intra-ordinal relationships, discuss the evolution of their morphologi
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27. Extinction of Harrington's mountain goat
Keratinous horn sheaths of the extinct Harrington's mountain goat, Oreamnos harringtoni, were recovered at or near the surface of dry caves of the Grand Canyon, Arizona. Twenty-three separate specimens from two caves were dated nondestructively by the tandem accelerator mass spectrometer (TAMS). Both the TAMS and the conventional dates indicate that Harringt
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28. Comparative aspects of trophoblast development and placentation
Based on the number of tissues separating maternal from fetal blood, placentas are classified as epitheliochorial, endotheliochorial or hemochorial. We review the occurrence of these placental types in the various orders of eutherian mammals within the framework of the four superorders identified by the techniques of molecular phylogenetics. The superorder A
BioMed Central.
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29. Loss of teeth and enamel in tetrapods: fossil record, genetic data and morphological adaptations
Since their recruitment in the oral cavity, approximately 450 million years ago, teeth have been subjected to strong selective constraints due to the crucial role that they play in species survival. It is therefore quite surprising that the ability to develop functional teeth has subsequently been lost several times, independently, in various lineages. In th
Blackwell Science Inc.