Dorudon Gibbes 1845

Abstract

Genus Dorudon Gibbes, 1845 Dorudon Gibbes, 1845: 254. Dorydon Pictet, 1853: 378. Doryodon Cope, 1868: 154-155. Durodon Gill, 1872: 93. Prozeuglodon Andrews, 1906: 243. TYPE SPECIES. — Dorudon serratus by original designation. REFERRED SPECIES. — Dorudon atrox. AMENDED DIAGNOSIS. — Adult Dorudon are mid-sized basilosaurids (condylobasal length c. 85 cm; Kellogg 1936; Uhen 2004), smaller than Basilosaurus (Kellogg 1936), Basiloterus (Gingerich et al. 1997), Eocetus (Gingerich & Zouhri 2015), Cynthiacetus spp. (Martínez-Cáceres et al. 2017), Perucetus (Bianucci et al. 2023) and Masracetus (Gingerich 2007), larger than Chrysocetus (Uhen & Gingerich 2001), Saghacetus (Martínez-Cáceres et al. 2017), Ocucajea (Uhen et al. 2011), Stromerius (Gingerich 2007), and Tutcetus (Antar et al. 2023). The posterior narial region of Dorudon is characterized by: narial processes of the premaxillae which extend along c. 2/3 of the length of the nasals (shared with Cynthiacetus spp., Basilosaurus spp., Ocucajea; this study), medial margins of the maxillae which do not contact the frontals (shared with Cynthiacetus spp., Basilosaurus spp., Ocucajea; this study). The occipital shield is anterodorsally oriented (differing from Cynthiacetus spp., Saghacetus; this study), and the nuchal crest lacks a posteriorly projecting point at mid-height (this study). The tympanic bulla of Dorudon lacks the squared shape typical of Supayacetus (Uhen et al. 2011). The dentition of Dorudon is characterized by an enamel with fine vertical striae, and a cingulum that is distinctly smaller than that of Zy. kochii and lacks crenulations. The p1 of Dorudon is double-rooted (differing from Zy. kochii). The manubrium lacks the characteristic T-shape of Supayacetus (Uhen et al. 2011), and Pachycetus (Gol’din et al. 2014). The posterior thoracic, lumbar, and caudal vertebrae show no elongation, with the height, width and length of centra being approximately equal, differing from Pachycetinae (Gingerich et al. 2022), Basilosaurus spp. (Kellogg 1936; Uhen 2013a), Basiloterus (Gingerich et al. 1997), Eocetus (Gingerich & Zouhri 2015), Saghacetus (Martínez-Cáceres et al. 2017), and Stromerius (Gingerich 2007). The neural arches are likewise not elongated, and no sign of pachyostosis is notable (differing from Pachycetinae; Gingerich et al. 2022). The metapophyses on the lumbar vertebrae are not anteriorly elongated (differing from Stomerius; Gingerich 2007).

Authors 3

1. Jonas W. P. Hakkens

   Utrecht University

   Affiliation as printed

   Utrecht University, Faculty of Geosciences, Department of Earth Sciences, Princetonlaan 8 a, 3584 CB Utrecht (the Netherlands) j. w. p. hakkens @ students. uu. nl and jonashakkens @ gmail. com (corresponding author)

2. Jelle W. F. Reumer Aachen Faculty of Geosciences Department of Earth Sciences

   Utrecht University · Naturalis Biodiversity Center · Natural History Museum Rotterdam

   Affiliation as printed

   Utrecht University, Faculty of Geosciences, Department of Earth Sciences, Princetonlaan 8 a, 3584 CB Utrecht (the Netherlands) and Naturalis Biodiversity Center, Darwinweg 2, 2333 CR, Leiden (the Netherlands) and Natural History Museum Rotterdam, Westzeedijk 345, 3015 AA, Rotterdam (the Netherlands) j. w. f. reumer @ uu. nl

3. Anne S. Schulp Aachen Faculty of Geosciences Department of Earth Sciences

   Utrecht University · Naturalis Biodiversity Center · Teylers Museum

   Affiliation as printed

   Utrecht University, Faculty of Geosciences, Department of Earth Sciences, Princetonlaan 8 a, 3584 CB Utrecht (the Netherlands) and Naturalis Biodiversity Center, Darwinweg 2, 2333 CR, Leiden (the Netherlands) and Teylers Museum, Spaarne 16, 2011 CH, Haarlem (the Netherlands) a. s. schulp @ uu. nl