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Conservation of placentation during the tertiary radiation of mammals in South America.
MedLine Citation:
PMID:  23355381     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The eutherian placenta is considered to possess great plasticity, but it is not clear how this variation reflects adaptation to different ecological niches. Because South America was isolated for most of the Tertiary, it represents a natural laboratory to examine this question. We here describe placentation in three South American groups: Xenarthra have been part of the fauna from at least the mid-Paleocene whereas caviomorph rodents and Neotropical primates are each derived from a single founder that reached South America in the Eocene and Oligocene, respectively. The common ancestor of Xenarthra had a villous, haemochorial placenta, from which the labyrinthine, endotheliochorial placenta of sloths later evolved. Placentation in Caviomorpha follows an extraordinary stable pattern, characterized by a haemomonochorial, labyrinthine and highly lobed structure with specialized growing areas. This pattern was present before arrival of these rodents in South America and enabled a successful radiation especially during the spread of grasslands. Neotropical primates have haemochorial, trabecular placentas with a specialized maternal blood supply; a pattern that contrasts with that of Old World monkeys and may have been present in the founder generation on arrival in South America. In conclusion, there is a dichotomy within Xenarthra but otherwise the ancient South American mammals do not show much variation in principal placental characters. Thus, the successful radiation of these three groups, and their adaptation to diverse ecological niches, did not require substantial alterations in placentation. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.
Authors:
Anthony Michael Carter; Andrea Maria Mess
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-28
Journal Detail:
Title:  Journal of morphology     Volume:  -     ISSN:  1097-4687     ISO Abbreviation:  J. Morphol.     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0406125     Medline TA:  J Morphol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2013 Wiley Periodicals, Inc.
Affiliation:
Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark. acarter@health.sdu.dk.
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