Panciroli, Elsa, Schultz, Julia A and Luo, Zhe-Xi (2019) Morphology of the petrosal and stapes of Borealestes (Mammaliaformes, Docodonta) from the Middle Jurassic of Skye, Scotland. Papers in Palaeontology, 5 (1). pp. 139-156. ISSN 2056-2802

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We describe, in unprecedented detail, the petros-als
and stapes of the docodont Borealestes from the Middle
Jurassic of Scotland, using high resolution lCT and phase-
contrast synchrotron imaging.

We describe the inner ear endocast and the vascularized interior structure of the pet-rosal, and provide the first endocranial view of a docodontan petrosal.

Our study confirms some similarities in petrosal and stapedial morphology with the better known Haldan-odon of the Late Jurassic of Portugal, including: (1) the degree of curvature of the cochlea;

(2) multiple features related to the highly pneumatized paroccipital region;

(3) the shape of lateral trough, the fossa of the M. tensor tym-pani, and the ridge on the promontorium;

(4) the round shape of the fenestra vestibuli; and

(5) overall morphology of the stapes. But Borealestes differs from Haldanodon in having a bony ridge that separates the tympanic opening of the prootic canal, the secondary facial foramen and the hia-tus Fallopii, from the fenestra vestibuli.

We identify two new vascular structures: the anterior and posterior trans-cochlear sinuses, which traverse the pars cochlearis around the cochlear nerve (VIII). These trans-cochlear sinuses have not been observed in previous docodont specimens, and could be an autapomorphy of Borealestes, or apomorphic for this clade.

We also establish the anatomical relationship of the
circum-promontorium plexus to the inner endocast. The
high quality of our scans has made these structures visible
for the first time.

Item Type: Article
Uncontrolled Keywords: Borealestes, Mammaliaformes, docodont, pet-rosal, inner ear, endocast
Subjects: D History General and Old World > DA Great Britain
Q Science > QL Zoology
Theme: Understanding the natural world
Department: Natural Sciences
Related URLs:
Depositing User: Ross Anderson
Date Deposited: 05 Nov 2018 12:50
Last Modified: 05 Apr 2019 11:56

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