New species of mammaliaform and the cranium of Borealestes (Mammaliformes: Docodonta) from the Middle Jurassic of the British Isles Author Panciroli, Elsa Author Benson, Roger B. J. Author Fernandez, Vincent Author Butler, Richard J. Author Fraser, Nicholas C. Author Luo, Zhe-Xi Author Walsh, Stig text Zoological Journal of the Linnean Society 2021 2021-01-27 192 4 1323 1362 http://dx.doi.org/10.1093/zoolinnean/zlaa144 journal article 2567 10.1093/zoolinnean/zlaa144 eee94db3-df5c-46ee-92a7-fb23e558f663 0024-4082 5856067 320C0FA6-04F0-4D5C-93BF-D14160AFBB4F DOBUNNODON MUSSETTAE (SIGOGNEAU- RUSSELL, 2003) COMB. NOV. BOREALESTES MUSSETTI SIGOGNEAU- RUSSELL, 2003 BOREALESTES MUSSETTAE AVERIANOV, 2004 (EMENDED GENDER) Holotype : NHMUK PV M46495 , a right lower molar ( Fig. 5C 1–4 ). Stratigraphic provenance: Forest Marble Formation, Late Bathonian, Middle Jurassic ( Retrocostatum Zone: Barron et al. , 2012 ). Ty p e l o c a l i t y: K i r t l i n g t o n C e m e n t Q u a r r y, Oxfordshire , UK . Referred material: From the Forest Marble Formation of Kirtlington , Oxfordshire : NHMUK PV M46224 , NHMUK PV M46239 , NHMUK PV M46001 , NHMUK PV M46066 , NHMUK PV M46836 , NHMUK PV M46319 , NHMUK PV M46809 and NHMUK PV M46835 , all lower molars. From the Forest Marble Formation of Watton Cliff , Dorset : NHMUK PV M46001 , lower molar . Etymology: The species name was given in honour of Dr Frances Mussett for her ‘major participation in the accumulation of the Kirtlington fauna’ (Sigogneau-Russell, 2003). Differential diagnosis: Dobunnodon mussettae resembles other docodontans in that it possesses an anterior ‘pseudotalonid basin’ on the lower molars, formed by cusps a, b, and g, has cusps b–a–c in a triangular arrangement, the lower molars are elongated anteroposteriorly, with labial row of higher cusps arranged in anteroposterior alignment with largest cusp a, and it has a lingual row of smaller cusps with distinctive anterior cusp g and larger posterior cusp c. The lower molar of Dobunnodon is unlike most docodontans, but is similar to Tashkumyrodon in being mediolaterally compressed. It resembles most docodontans, but differs from Borealestes in that the a–g crest is present on both cusp g and cusp a, and in having a strong a–d crest on cusp a ( Fig. 5c ). Cusp g is slightly more developed, and cusps c and g are placed further apart anteroposteriorly, than in Borealestes . Unlike Simpsonodon , Agilodocodon and Docodon , but like most other docodontans, Dobunnodon lacks creases and pits’ ‘ornamentation’ on the teeth. Dobunnodon has an anterior lingual cingulid that passes below cusp g to midway along the molar anteroposteriorly. The df cusp is more developed in Dobunnodon than in Borealestes and is distinct from the d cusp. Cusp e is positioned in alignment with the anteroposterior axis of the molar, whereas cusp e is lingual of the anteroposterior axis on molars of Borealestes . The upper molars are not yet known for this taxon. Description: The holotype NHMUK PV M46495 , is a single, right, lower molar, lacking a root and broken at the base of cusp a (reconstructed for Fig. 5C ), previously described by Sigogneau-Russell (2003) and Panciroli et al. (2019) .