Talk:Platypus 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, September 17) Embryology Platypus Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Platypus_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 Institut für Spezielle Zoologie und Evolutionsbiologie, Friedrich-Schiller Universität Jena, Erbertstr.1, 07743 Jena, Germany E-mail: 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.

© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

PMID: 21521190

2010

Early development and embryology of the platypus

Hughes RL, Hall LS. Philos Trans R Soc Lond B Biol Sci. 1998 Jul 29;353(1372):1101-14. Review. PMID: 9720108

Cereb Cortex. 2010 May;20(5):1071-81. Epub 2009 Sep 2. The subventricular zone is the developmental milestone of a 6-layered neocortex: comparisons in metatherian and eutherian mammals. Cheung AF, Kondo S, Abdel-Mannan O, Chodroff RA, Sirey TM, Bluy LE, Webber N, DeProto J, Karlen SJ, Krubitzer L, Stolp HB, Saunders NR, Molnár Z.

Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK. Abstract The major lineages of mammals (Eutheria, Metatheria, and Monotremata) diverged more than 100 million years ago and have undergone independent changes in the neocortex. We found that adult South American gray short-tailed opossum (Monodelphis domestica) and tammar wallaby (Macropus eugenii) possess a significantly lower number of cerebral cortical neurons compared with the mouse (Mus musculus). To determine whether the difference is reflected in the development of the cortical germinal zones, the location of progenitor cell divisions was examined in opossum, tammar wallaby, and rat. The basic pattern of the cell divisions was conserved, but the emergence of a distinctive band of dividing cells in the subventricular zone (SVZ) occurred relatively later in the opossum (postnatal day [P14]) and the tammar wallaby (P40) than in rodents. The planes of cell divisions in the ventricular zone (VZ) were similar in all species, with comparable mRNA expression patterns of Brn2, Cux2, NeuroD6, Tbr2, and Pax6 in opossum (P12 and P20) and mouse (embryonic day 15 and P0). In conclusion, the marsupial neurodevelopmental program utilizes an organized SVZ, as indicated by the presence of intermediate (or basal) progenitor cell divisions and gene expression patterns, suggesting that the SVZ emerged prior to the Eutherian-Metatherian split.

PMID: 19726493