The bushy-tailed opossum, Glironia, has odd teeth

Figure 1. Gliornia venusta, the extant bushy opossum, in vivo. ” data-image-caption=”

Figure 1. Gliornia venusta, the extant bushy opossum, in vivo.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/08/glironia_venusta.jpeg?w=203″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/08/glironia_venusta.jpeg?w=203″ tabindex=”0″ role=”button” class=”wp-image-88446 size-full” src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/08/glironia_venusta.jpeg” alt=”Figure 1. Gliornia venusta, the extant bushy opossum, in vivo.” width=”203″ height=”248″ />

Figure 1. Gliornia venusta, the extant bushy-tailed opossum, in vivo, smaller than life size = 20 cm snout-vent length.

In all tetrapods
premaxillary teeth arise from the premaxilla. These are called incisors in mammals because they usually have a distinct shape, whatever that shape might be. Shapes  and numbers vary.

The first tooth in the maxilla is the canine.
Typically it is cone-shaped and larger than the incisors. Following the canine are premolars and molars. Typically these are also shorter than the canine and have two+ tooth roots.

Extant Glironia is an exception.
Here (Fig 2) the canine, the first tooth in the maxilla (orange), is short and incisor shaped. The first of three premolars (blue) is large and sharp, like a typical canine. On the mandible the situation is similar and, therefore, just as odd. The LRT scores for premaxillary tooth counts and number of molars.

Figure 2. Glironia skull and tooth row (right, rotated). ” data-image-caption=”

Figure 2. Glironia skull and tooth row (right, rotated).

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/08/glironia_venusta588-1.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/08/glironia_venusta588-1.jpg?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-88444″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/08/glironia_venusta588-1.jpg” alt=”Figure 2. Glironia skull and tooth row (right, rotated). ” width=”584″ height=”561″ />

Figure 2. Glironia skull and tooth row (right, rotated).

These are the ‘little things’
that were overlooked earlier and need to be repaired in order to score taxa correctly in the large reptile tree, (LRT, 2322 taxa) which has been updated AGAIN today.

The LRT will be updated again and again until the MPTs are reduced as much as possible. One MPT would be ideal, but may be unattainable.

Mistakes, like this one (Fig 2) are discovered every day.
When that stops happening, I’ll let you know.

Every day there is something to be learned. The tree topology is getting sturdier.

Glironia venusta
(Thomas 1912; snout-vent length 20cm) is the extant bushy-tailed opossum. It is nocturnal, arboreal, small and omnivorous. Here it nests with Late Jurassic Henkelotherium and Middle Jurassic Agilodocodon – and therefore probably had its own genesis in the Jurassic.Glironia lacks a marsupium (= pouch), by convergence with placentals, Descendant taxa, like Dromiciops, retain a pouch, so Glironia lost its pouch all by itself since the Jurassic.

References
Thomas O 1912. A new Genus of Opossums and a new Tuco-tuco. The Annals and Magazine of Natural History. Ser. 8. 9 (50): 239–241. doi:10.1080/00222931208693127

wiki/Glironia