Monotreme ossification sequences and the riddle of mammalian skeletal development

Weisbecker, Vera (2011) Monotreme ossification sequences and the riddle of mammalian skeletal development. Evolution, 65 5: 1323-1335. doi:10.1111/j.1558-5646.2011.01234.x


Author Weisbecker, Vera
Title Monotreme ossification sequences and the riddle of mammalian skeletal development
Journal name Evolution   Check publisher's open access policy
ISSN 0014-3820
1558-5646
Publication date 2011-05
Sub-type Article (original research)
DOI 10.1111/j.1558-5646.2011.01234.x
Volume 65
Issue 5
Start page 1323
End page 1335
Total pages 13
Place of publication Oxford, England, U.K.
Publisher Wiley-Blackwell Publishing
Collection year 2012
Language eng
Formatted abstract
The developmental differences between marsupials, placentals, and monotremes are thought to be reflected in differing patterns of postcranial development and diversity. However, developmental polarities remain obscured by the rarity of monotreme data. Here, I present the first postcranial ossification sequences of the monotreme echidna and platypus, and compare these with published data from other mammals and amniotes. Strikingly, monotreme stylopodia (humerus, femur) ossify after the more distal zeugopodia (radius/ulna, tibia/fibula), resembling only the European mole among all amniotes assessed. European moles also share extreme humeral adaptations to rotation digging and/or swimming with monotremes, suggesting a causal relationship between adaptation and ossification heterochrony. Late femoral ossification with respect to tibia/fibula in monotremes and moles points toward developmental integration of the serially homologous fore- and hindlimb bones. Monotreme cervical ribs and coracoids ossify later than in most amniotes but are similarly timed as homologous ossifications in therians, where they are lost as independent bones. This loss may have been facilitated by a developmental delay of coracoids and cervical ribs at the base of mammals. The monotreme sequence, although highly derived, resembles placentals more than marsupials. Thus, marsupial postcranial development, and potentially related diversity constraints, may not represent the ancestral mammalian condition
Keyword Echidna
Heterochrony
Life history
Marsupials
Ossification
Platypus
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Non HERDC
School of Biological Sciences Publications
 
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Created: Fri, 23 Mar 2012, 15:51:30 EST by Gail Walter on behalf of School of Biological Sciences