Document Detail

Description of a cranial endocast from a fossil platypus, Obdurodon dicksoni (Monotremata, Ornithorhynchidae), and the relevance of endocranial characters to monotreme monophyly.
MedLine Citation:
PMID:  16710845     Owner:  NLM     Status:  MEDLINE    
A digital cranial endocast of the Miocene platypus Obdurodon dicksoni was extracted from high-resolution X-ray computed tomography scans. This endocast represents the oldest from an unequivocal member of either extant monotreme lineage and is therefore important for inferring character support for Monotremata, a clade that is not well diagnosed. We describe the Obdurodon endocast with reference to endocasts extracted from skulls of the three species of extant monotremes, particularly Ornithorhynchus anatinus, the duckbill platypus. We consulted published descriptions and illustrations of whole and sectioned brains of monotremes to determine which external features of the nervous system are represented on the endocasts. Similar to Ornithorhynchus, well-developed parafloccular casts and reduced olfactory bulb casts are present in the Obdurodon endocast. Reduction of the olfactory bulbs in comparison with tachyglossids and therian mammals is a potential apomorphy for Ornithorhynchidae. The trigeminal nuclei, ganglia, and nerves (i.e., trigeminal complex) are enlarged in Obdurodon, as evidenced by their casts on the endocast, as is the case in the extant platypus. The visibility of enlarged trigeminal nucleus casts on the endocasts of Obdurodon and Ornithorhynchus is a possible synapomorphy of Ornithorhynchidae. Electroreception and enlargement of the trigeminal complex are possible synapomorphies for Monotremata.
Thomas E Macrini; Timothy Rowe; Michael Archer
Related Documents :
18997285 - Free radical scavenging activity, metal chelation and antioxidant power of some of the ...
7353455 - Esophageal food impaction: description of a new method for bolus removal.
16719535 - Antioxidant activity and polyphenol and procyanidin contents of selected commercially a...
22428565 - Review article: intestinal lymphoid nodular hyperplasia in children - the relationship ...
11586765 - Nondestructive indices of trace element exposure in squamate reptiles.
3396735 - Effects of food components and additives on the formation of nitrosamides.
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of morphology     Volume:  267     ISSN:  0362-2525     ISO Abbreviation:  J. Morphol.     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2006-08-14     Completed Date:  2006-09-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0406125     Medline TA:  J Morphol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1000-15     Citation Subset:  IM    
Copyright Information:
Copyright 2006 Wiley-Liss, Inc.
Jackson School of Geosciences and University of Texas High-Resolution X-ray Computed Tomography Facility, University of Texas at Austin, 78712, USA.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Monotremata / anatomy & histology
Platypus / anatomy & histology*
Skull / anatomy & histology*,  radiography
Species Specificity

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Jaw muscle functional anatomy in northern grasshopper mouse, Onychomys leucogaster, a carnivorous mu...
Next Document:  Nitric oxide donor molsidomine attenuates psychotomimetic effects of the NMDA receptor antagonist MK...