Mammals

John Wible, PhD

The Bones of the Skull of the Short-tailed Opossum Monodelphis brevicaudata (Didelphidae, Marsupialia) skull 

In the August 27, 2003, issue of Annals of Carnegie Museum, curator John R. Wible describes and illustrates in detail the exterior bones of the skull of this small South American opossum, close relative of the now-popular laboratory mammal Monodelphis domestica. He also standardizes terminology for the numerous cranial foramina that transmits nervous and vascular structures to and from the skull. This study represents one of the few such resources for scientists and students other than veterinary textbooks on domesticated mammals.

This web page includes an alphabetical listing of the bones of the skull and some of the illustrations from this paper, all by Gina Scanlon. The figured specimen is one of 55 examples of the genus Monodelphis in the collections of the Section of Mammals. Direct queries to WibleJ@carnegiemnh.org. For more information, see the original reference: Wible, J. R. 2003. On the cranial osteology of the short-tailed opossum Monodelphis brevicaudata (Didelphidae, Marsupialia). Annals of Carnegie Museum 72 (3): 1-66.

This web page is also available as a file. Click here to download (Microsoft Word, 185 Kb).

Click on figure numbers for further information on characters.

Alisphenoid – (figs. 1, 2, 3, 4: as) paired, endochondral bone in the skull base and br aincase wall.

Basioccipital – (fig. 2, 3: bo) unpaired, endochondral bone in the skull base.

Basisphenoid – (figs. 2, 3, 5: bs) unpaired, endochondral bone in the skull base.

Ectotympanic – (figs. 2, 3, 4, 5: ec) paired, intramembranous bone in the skull base (ear region).

Exoccipital – (figs. 2, 3, 4, 6: eo) paired, endochondral bone in the skull base and occiput.

Frontal – (figs. 1, 4, 5: fr) paired, intramembranous bone in the skull roof and orbit.

Incus – (figs. 3,5: i) paired, endochondral bone in the ear region.

Interparietal – (figs. 1, 4: ip) unpaired, intramembranous bone in the skull roof.

Jugal – (figs. 1, 2, 3, 4, 5: ju) paired, intramembranous bone in the zygomatic arch.

Lacrimal – (figs. 1, 2, 4, 5: lac) paired, intramembranous bone in the face and orbit.

Malleus – (figs. 3, 5: m) paired, endochondral bone in the ear region.

Mandible – (fig. 4, unlabelled) paired, intramembranous bone of the lower jaw containing four incisors, one canine, three premolars, and four molars.

Maxilla – (figs.1, 2, 4, 5: mx) paired, intramembranous bone in the palate and face containing the canine, three premolars, and four molars.

Nasal – (figs. 1, 4, 5: na) paired, intramembranous bone in the roof of the nasal cavity.

Orbitosphenoid – (fig. 5: os) paired, endochondral bone in the orbit.

Palatine – (figs. 2, 4, 5: pal) paired, intramembranous bone in the palate and orbit.

Parietal – (figs. 1, 4, 5: pa) paired, intramembranous bone in the skull roof.

Petrosal – (figs. 2, 3 [not labelled], 4, 6: pe) paired, endochondral bone in the skull base (ear region) and occiput.

Premaxilla – (figs. 1, 2, 4: pmx) paired, intramembranous bone in the palate and face containing five incisors.

Presphenoid – (figs. 2, 5:ps) unpaired, endochondral bone in the skull base and nasal cavity.

Pterygoid – (figs. 2, 3, 4, 5: pt) paired, intramembranous bone in the skull base.

Squamosal – (figs. 1, 2, 3, 4, 5, 6: sq) paired, intramembranous bone in the skull base and braincase wall.

Supraoccipital – (figs. 4, 6: so) unpaired, endochondral bone in the occiput.

Stapes – (fig. 3: s) paired, endochondral bone in the ear region.

Vomer – (not figured) unpaired, intramembranous bone in the nasal cavity.