Eurotherium theriodis ( Van Valen, 1965 )

Dubied, Morgane, Solé, Floreal & Mennecart, Bastien, 2021, Endocranium and ecology of Eurotherium theriodis, a European hyaenodont mammal from the Lutetian, Acta Palaeontologica Polonica 66 (3), pp. 545-554 : 547-549

publication ID	https://doi.org/ 10.4202/app.00771.2020
persistent identifier	https://treatment.plazi.org/id/03F9B80C-D542-FFA2-FCC3-FA99FE0A98D6
treatment provided by	Felipe
scientific name	Eurotherium theriodis ( Van Valen, 1965 )
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Eurotherium theriodis ( Van Valen, 1965)

Material.— NMB.Em12 (holotype), a complete skull bearing right P3–P4 and M1, left P1–P4 and M1, and roots of right P1–P2; from? Egerkingen γ, Switzerland, Lutetian , MP13 ?.

Description.— Endocranium: The olfactory bulbs (maximum length 14 mm, maximum width 20 mm) are tube-shaped ( Fig. 3A View Fig 1 View Fig ). Olfactory tubercles are visible in ventral view ( Fig. 3A View Fig 2 View Fig ). The encephalon is spherical, but its anterior part has no visible structure due to taphonomic modification; for instance, the anterior lobes are not observable due to poor preservation. The cerebrum (maximum length 22 mm, maximum width 34 mm) is similar in width to the cerebellum (maximum length 13 mm, maximum width 37 mm). The cerebrum is divided into two hemispheres ( Fig. 3A View Fig 1 View Fig ). The sagittal sinus is present but weakly marked. A slight protuberance, which may be the result of damage during preservation, is present on the left side of the cerebrum, preventing observation of the different furrows on this side of the cerebrum. On the right side of the cerebrum, the lateral sulci are sigmoidal, with their anterior part concave ( Fig. 3A 3 View Fig ). The suprasylvian sulci are concavely rounded and become rectilinear in their anterior part

Fig. 3A 3 View Fig ). Their exact course is difficult to define given the preservation of the specimen. The cerebellum is transversally wide. However, it is poorly preserved, which prevents a precise description of its morphology. We can only determine the presence of the vermis ( Fig. 3A 3 View Fig ) and of the medulla oblongata ( Fig. 3A View Fig 1 View Fig , A 2 View Fig ). The preservation of the ventral part of the encephalon does not allow for description of all the nerves and sinuses ( Fig. 3A View Fig 2 View Fig ). The anterior side of the ventral part is the best preserved ( Fig. 3A View Fig 2 View Fig ). In ventral view, the pituitary appears between the canals for cranial nerves III, IV, and V 1. Cranial nerve II stands out clearly on the anterior and relatively axial part of the encephalon. Just behind this, cranial nerves III, IV, V 1, V 2, and VI are located in a single expanded and curved canal ( Fig. 3A View Fig 2 View Fig ). The preservation of the posterior part does not allow for further description of these nerve structures. The cerebellum is broken and heavily restored, preventing any description. The only element that can be distinguished is the vermis, but the latter cannot be described in detail.

Nasal cavity: The study of the nasal cavity allows the recognition of five turbinates on each side of the rostrum; they are visible in dorsal view ( Fig. 3A View Fig 1 View Fig ). The latter are non-rectilinear and are separated from each other. The mesethmoid appears thin and elongated ( Fig. 3A View Fig 1 View Fig ). The turbinates widen and thicken towards the front of the skull, forming two fans (diverging 5–35° from the median axis). They thus form a considerable volume with significant relief; this volume is large compared to the encephalon.

Stratigraphic and geographic range.—Lutetian,? MP 13– M14; Switzerland and France.