Talk:Echidna Development

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On this website the Discussion Tab or "talk pages" for a topic has been used for several purposes: References - recent and historic that relates to the topic Additional topic information - currently prepared in draft format Links - to related webpages Topic page - an edit history as used on other Wiki sites Lecture/Practical - student feedback Student Projects - online project discussions. Links: Pubmed Most Recent \| Reference Tutorial \| Journal Searches Glossary Links Glossary: A \| B \| C \| D \| E \| F \| G \| H \| I \| J \| K \| L \| M \| N \| O \| P \| Q \| R \| S \| T \| U \| V \| W \| X \| Y \| Z \| Numbers \| Symbols \| Term Link Cite this page: Hill, M.A. (2026, October 1) Embryology Echidna Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Echidna_Development

2011

Monotreme ossification sequences and the riddle of mammalian skeletal development

Evolution. 2011 May;65(5):1323-35. doi: 10.1111/j.1558-5646.2011.01234.x. Epub 2011 Feb 18.

Weisbecker V. Source Earth Sciences, University of Cambridge, Downing St. CB2 3EQ, Cambridge, United Kingdom. vw248@cam.ac.uk

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.

PMID: 21521190 http://www.ncbi.nlm.nih.gov/pubmed/21521190

Talk:Echidna Development

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2011

Monotreme ossification sequences and the riddle of mammalian skeletal development