Revisiting the predatory metathere clade, Sparassodonta

Figure 1. A traditional selection of sparassodont metatheres.

Figure 1. A traditional selection of sparassodont metatheres from Forasieppi, MacPhee and del Pino 2019

In their study of the cranium
of the South American sparassodont sabertooth, Thylacosmilus, Forasieppi, MacPhee and del Pino 2019 report, “Sparassodonta is the group that includes the common ancestor of Patene and all its descendants. Undisputed records of Sparassodonta, including ones for Patene simpsoni, begin in the Early Eocene (Itaboraian) and extend through to the Pliocene (Chapadmalalan), when the last of them disappeared.”

FIgure 1. Cladogram of the traditional Sparassodonta from Babot and Forasiepi 2016. Taxa also found in the LRT are colored.

FIgure 2. Cladogram of the traditional Sparassodonta from Babot and Forasiepi 2016. Taxa also found in the LRT are colored. Compare to Figure 2. The Babot and Forasiepi 2016 cladogram includes tooth only and mandible only taxa.

A recent cladogram of Sparassodonta and its outgroups
(Fig. 1) was published in Babot and Forasiepi 2016 (Fig. 2). This cladogram is distinct from the large reptile tree (LRT, 1530 taxa), so no confirmation here.

FIgure 2. Subset of the LRT focusing on the clade Metatheria (Marsupialia). Taxa shared with Babot and Forasiepi 2016 are colored. Compared to Figure 1.

FIgure 3. Subset of the LRT focusing on the clade Metatheria (Marsupialia). Taxa shared with Babot and Forasiepi 2016 are colored. Compared to Figure 1. This cladogram includes relatively well-known and complete taxa.

Patene is known
from a tiny partial maxilla and mandible. I have not added it to the LRT. Mayulestes has just been downloaded, awaiting testing.

Figure 4. Thylacosmilus compared to Vincelestes separated by tens of millions of years. The both have maxillae conjoined dorsally to house the large canines.

Figure 4. Thylacosmilus compared to Vincelestes separated by tens of millions of years. The both have maxillae conjoined dorsally to house the large canines.

According to the LRT,
taxa missing from the Babot and Forasiepi tree include Vincelestes (a sister taxon to Thylacosmilus in the LRT) and a long list of other carnivorous marsupials. Hadrocodium is not included in Babot and Forasiepi. It attracts the other sabertooth, Patagosmilus (Fig. 5), as we learned earlier here.

Figure 1. Patagosmilus to scale alongside Hadrocodium. These sabetooth taxa are not directly related to Thylacosmilus in the LRT.

Figure 5. Patagosmilus to scale alongside Hadrocodium. These sabetooth taxa are not directly related to Thylacosmilus in the LRT.

FIgure 2b. Borhyaena skull cracked and angled to match the glenoid to the jaw joint, distinct from the original illustration (above).

FIgure 6. Borhyaena skull cracked and angled to match the glenoid to the jaw joint, distinct from the original illustration (above).

Late note: added the same evening as the original post:
Mayulestes ferox (Fig. 1) was just now added to the LRT, and it nests at the base of the Masrasector + Borhyaena clade. Nothing else changed. Thylacosmilus is still not related to  the dasyurids, including the creodonts and borhyaenids.


References
Babot J and Forasiepi AM 2016. Mamíferos predadores nativos del Cenozoico sudamericano: evidencias filogenéticas y paleoecológicas. Contributions del MACN 6 Historia evolutiva y paleobiogeografica de los vertebros de America del Sur. Agnolin FL et al. editors.
Forasiepi AM, MacPhee RDE and Hernandez del Pino 2019. Caudal cranium of Thylacosmilus atrox (Mammalia, Metatheria, Sparassodonta, a South American predaceous sabertooth. Bulletin of the American Museum of Natural History 433:1–64.

1 thought on “Revisiting the predatory metathere clade, Sparassodonta

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.