Another fang transition from maxilla to premaxilla

Recent housekeeping in the marsupial subset
of the large reptile tree (LRT, 2320 taxa) has revealed new insights into the rarely studied Eocene Thomashuxleya and Periphragnis (Fig 1) two robust, hippo-like marsupials derived from marsupial carnivores = creodonts.

Figure 1. A phylogenetic series that includes Thomashuxleya and Periphragnis. See figure 2 for a closeup of the double fang sets on Periphragnis, at the transition from maxillary fangs to premaxillary fangs. ” data-image-caption=”

Figure 1. A phylogenetic series that includes Thomashuxleya and Periphragnis. See figure 2 for a closeup of the double fang sets on Periphragnis, at the transition from maxillary fangs to premaxillary fangs.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/thomashuxleya.periphragnis588-1.jpg?w=72″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/thomashuxleya.periphragnis588-1.jpg?w=246″ tabindex=”0″ role=”button” class=”size-full wp-image-87424″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/thomashuxleya.periphragnis588-1.jpg” alt=”Figure 1. A phylogenetic series that includes Thomashuxleya and Periphragnis. See figure 2 for a closeup of the double fang sets on Periphragnis, at the transition from maxillary fangs to premaxillary fangs. ” width=”584″ height=”2429″ />

Figure 1. A phylogenetic series that includes Thomashuxleya and Periphragnis. See figure 2 for a closeup of the double fang sets on Periphragnis, at the transition from maxillary fangs to premaxillary fangs.

This hypothesis of interrelationships
updates all prior hypotheses published online in the LRT. This evolutionary sequence is analogous to a similar sequence in the Condylarthra, which also turned a lineage of carnivorous mammals into bulky terrestrial herbivores, like hippos, uinatatheres, etc.

Figure 2. Patriofelis skull in two views. Colors added here. ” data-image-caption=”

Figure 2. Patriofelis skull in two views. Colors added here.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/patriofelis-skull-anterior-view588.gif?w=199″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/patriofelis-skull-anterior-view588.gif?w=584″ tabindex=”0″ role=”button” class=”size-full wp-image-87428″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/patriofelis-skull-anterior-view588.gif” alt=”Figure 2. Patriofelis skull in two views. Colors added here. ” width=”584″ height=”882″ />

Figure 2. Patriofelis skull in two views. Colors added here.

Patriofelis (Fig 2) and probably Thomashuxleya
precede this transition of fangs from the maxilla to the premaxilla. Closely related Periphragnis (Figs 1, 3) is the transitional taxon. Derived taxa, like Hegetotherium and Mesotherium reduce and lose the maxilla canine.

Figure 1. A phylogenetic series that includes Thomashuxleya and Periphragnis. See figure 2 for a closeup of the double fang sets on Periphragnis, at the transition from maxillary fangs to premaxillary fangs. ” data-image-caption=”

Figure 2. Periphragnis jaws showing the dual fang sets arising from the maxilla and premaxilla.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/periphragnis-canines300.gif?w=168″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/periphragnis-canines300.gif?w=300″ tabindex=”0″ role=”button” class=”size-full wp-image-87426″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/07/periphragnis-canines300.gif” alt=”Figure 1. A phylogenetic series that includes Thomashuxleya and Periphragnis. See figure 2 for a closeup of the double fang sets on Periphragnis, at the transition from maxillary fangs to premaxillary fangs. ” width=”300″ height=”535″ />

Figure 3. Periphragnis jaws showing the dual fang sets arising from the maxilla and premaxilla.

Periphragnis exauctus
(Roth 1899 (genus), Ameghino 1902 (species), Middle Eocene to Early Oligocene; 1.5m long), is traditionally considered very close to Thomashuxleya. It has five hoof-like unguals on all four extremities. Here Periphragnis is a transitional taxon with four fangs, two on the premaxilla and two on the maxilla.

Wikipedia – Patriofelis reports
“Patriofelis is an extinct genus of large, cat-like predatory placental mammals from extinct subfamily Oxyaeninae from the early to middle Eocene.”

A  marsupial mammal in the LRT

Patriofelis was featured in a YouTube video
interview on Palaeo Talks episode 58 with guest Riley Black, who considered Patriofelis to be a turtle-crushing panther analog.

References
Ameghino F 1882. Ungulata, Typotheria, Interatheridae. Catalog de la Prov. de Buenos Aires en la Expedicion Cont. Sud-America. March 1882. Boletino Instituto Geologia Argentino, June 1882. Cont. Conocimenient Mamif. Fosil. Repub. Argentina, in Accd. Nac. Cien., Cordoba 6:474-480. 1889.
Ameghino F 1887. Observaciones generales sobre el orden de mamíferos estinguidos sud-americanos llamados toxodontes (Toxodontia) y sinopsis de los géneros y especies hasta ahora conocidos. Anales del Museo de La Plata 1:1-66.
Ameghino F 1894. Enumeration synoptique des especes de mammifères fossiles des formations éocènes de Patagonie. Boletin de la Academia Nacional de Ciencias en Cordoba (Republica Argentina) 13:259-452.
Ameghino F 1901. Notices préliminaires sur des ongulés nouveaux des terrains crétacés de Patagonie [Preliminary notes on new ungulates from the Cretaceous terrains of Patagonia]. Boletin de la Academia Nacional de Ciencias de Córdoba 16:349-429.
Ameghino F 1902. Cuadro sinoptico de las formaciones sedimentarias terciarias y cretacicas de la Argentina, en relacion con el desarrollo y descendencia de los mamiferos. An. Mus. Nac. Hist. Nat., vol. 8, pp. 1-12.
Carrillo JD and Asher RJ 2017. An exceptionally well-preserved skeleton of Thomashuxleya externa (Mammalia, Notoungulata) from the Eocene of Patagonia, Argentina. Palaentologia Electronica 20.2.34A online PDF
Croft DA 2007. The Middle Miocene (Laventan) Quebrada Honda wildlife, southern Bolivia and a description of ITS Notoungulates. Palaeontology 50(1):277-303.
Roth S 1899. Aviso preliminar sobre mamíferos mesozoicos encontrados en Patagonia. Revista del Museo de La Plata 9: 381–388.
Seoane FD, Cerdeño E 2019. Systematic revision of Hegetotherium and Pachyrukhos (Hegetotheriidae, Notoungulata) and a new phylogenetic analysis of Hegetotheriidae. Journal of Systematic Palaeontology. in press. doi:10.1080/14772019.2018.1545146.
Stirton RA 1953. A new genus of interatheres from the Miocene of Colombia. University of California Publications in Geological Sciences 29: 265-348.
Serres E 1867. De l’ostéographie du Mesotherium et ses affinités zoologiques. Comptes Rendus de l’Académie des Sciences de Paris: 140-148, t. 65.
Spencer WB 1896. Report on the Work of the Horn Scientific Expedition to Central Australia. Four Volumes. London: Dulau and Co.

wiki/Interatherium
wiki/Mesotherium
wiki/Hegetotherium
wiki/Thomashuxleya
wiki/Protypotherium
wiki/Miocochilius
wiki/Periphragnis