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Eosqualodon
Taxonomy
Eosqualodon was named by Rothausen (1968) [Sepkoski's age data: T Ol-u Sepkoski's reference number: 746]. Its type is Eosqualodon langewieschei. It was considered monophyletic by Muizon (1987).
It was assigned to Squalodontinae by Rothausen (1968); to Cetacea by Sepkoski (2002); to Odontoceti by Geisler and Sanders (2003); and to Squalodontidae by Whitmore and Sanders (1977), Pilleri (1985), Muizon (1987), Carroll (1988), Muizon (1990), Benton (1993), Muizon (1994), McKenna and Bell (1997), Fordyce and de Muizon (2001), Uhen (2008), Fornasiero and Del Vavero (2014), Marx et al. (2016), Nelson et al. (2025), Nelson et al. (2025), Nelson et al. (2025).
It was assigned to Squalodontinae by Rothausen (1968); to Cetacea by Sepkoski (2002); to Odontoceti by Geisler and Sanders (2003); and to Squalodontidae by Whitmore and Sanders (1977), Pilleri (1985), Muizon (1987), Carroll (1988), Muizon (1990), Benton (1993), Muizon (1994), McKenna and Bell (1997), Fordyce and de Muizon (2001), Uhen (2008), Fornasiero and Del Vavero (2014), Marx et al. (2016), Nelson et al. (2025), Nelson et al. (2025), Nelson et al. (2025).
Species
E. langewieschei (type species), E. latirostris
Synonymy list
| Year | Name and author |
|---|---|
| 1968 | Eosqualodon Rothausen p. 88 figs. Fig. 1 |
| 1977 | Eosqualodon Whitmore and Sanders p. 305 |
| 1985 | Eosqualodon Pilleri p. 25 |
| 1987 | Eosqualodon Muizon p. 13 |
| 1988 | Eosqualodon Carroll |
| 1990 | Eosqualodon Muizon p. 315 figs. Fig. 15 |
| 1993 | Eosqualodon Benton p. 761 |
| 1994 | Eosqualodon Muizon p. 136 |
| 1997 | Eosqualodon McKenna and Bell p. 373 |
| 2001 | Eosqualodon Fordyce and de Muizon p. 178 |
| 2002 | Eosqualodon Sepkoski |
| 2003 | Eosqualodon Geisler and Sanders p. 28 |
| 2008 | Eosqualodon Uhen p. 445 figs. Table 1 |
| 2014 | Eosqualodon Fornasiero and Del Vavero p. 66 |
| 2016 | Eosqualodon Marx et al. p. 120 |
| 2025 | Eosqualodon Nelson et al. p. 3 figs. Figs. 2–11 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
G. †Eosqualodon Rothausen 1968
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†Eosqualodon langewieschei Rothausen 1968
†Eosqualodon latirostris Capellini 1903
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| M. D. Nelson et al. 2025 | Eosqualodon langewieschei is a medium-sized, longirostrine odontocete with a polydont and heterodont dentition. It is distinguished from the Patriocetidae and more stemward odontocetes by the posterolateral expansion of the ascending process of maxilla and frontal, the reduced intertemporal constriction, and the displacement of the parietal from the vertex. The following autapomorphies distinguish E. langewieschei from all other derived heterodont odontocetes, including Waipatiidae, Inticetidae, Phoberodon Cabrera, 1926, Prosqualodon Lydekker, 1893, and Squalodon: the coronoid process of the man- dible is sharply triangular with a laterally deflected apex, the supraoccipital projects anteriorly beyond the anterior margin of the subtemporal crest (a trait that also differentiates Eosqualodon from Ediscetus Albright et al., 2018, and Patriocetus Abel, 1914), a large foramen is present on the lateral surface of the parietal in the basicranium (also seen in ‘E.’ latirostris), and no ventral inflation is present on the ramus of the mandible (ambiguous in Inticetus Lambert et al., 2017).
Eosqualodon langewieschei is further differentiated from all other derived heterodont odontocetes except Squalodon spp. by synapomorphies of the Squalodontidae. Eosqualodon langewieschei possesses the following dentition per quadrant: 3 robust, procumbent incisors with striated enamel; 3–4 recurved single-rooted teeth; 3–4 triangular teeth with fused roots proximally; 5 posterior double-rooted teeth with 3–4 accessory cusps and rugose to nodular enamel. Further synapomorphies include: the dorsoventrally deep mesorostral canal, the presence of a dorsoventrally inflated maxillary flange, and the parietal forming a thickened, vascularized projection of bone med- ial to the periotic fossa. Eosqualodon langewieschei is further distinguished from Prosqualodon by the elongate rostrum comprising >60% of the condylobasal length (CBL), the narrower exposure of the frontal at the vertex, the absence of a rostral basin in the maxilla medial to the maxillary flange, the absence of an anterior projection of the antorbital process and slit-like antorbital notch, and the absence of external occipital crests on the supraoccipital. Eosqualodon langewieschei is additionally separated from Phoberodon by the absence of a cleft in the pre- maxilla at the vertex, the separation of the maxilla from the nuchal crest, and the robust mandibular condyle lacking a neck. Eosqualodon langewieschei is distinguished from the Inticetidae by the absence of a high rim surrounding the internal auditory meatus of the periotic, the shallow fovea epitubaria of the periotic, the lack of a developed lateral caudal tympanic process, the long tuberculum of the malleus, and the absence of a defined falcate process of the exoccipital. Eosqualodon langewieschei is distinguished from Waipatia Fordyce, 1994, and Otekaikea Tanaka and Fordyce, 2014, by the lack of a bifurcation of the posterior premaxilla by the maxilla into medial and lateral portions, the absence of a parabullary sulcus on the periotic, the absence of a shallow lateral groove on the periotic, the presence of a reniform fenestra rotunda of the periotic. Eosqualodon langewieschei can be further differentiated from Waipatia by the absence of a pronounced lateral tuberosity of the periotic; E. langewieschei differs from Otekaikea in that the vertex is not elevated above the dorsal margin of the temporal fossa (also distinguishing E. langewieschei from Prosqualodon), there is no posterior accessory foramen of the premaxilla, and the sternomastoid fossa on the zygomatic process of the squamosal is reduced. Most importantly, E. langewieschei is differentiated from species of its sister genus Squalodon by the fol- lowing traits of the tympanoperiotic complex: the absence of an anterior spine of the tympanic bulla, the deep and pronounced interprominential notch and median furrow of the tympanic bulla, the circular internal auditory meatus of the periotic, the absence of a ridge on the dorsal surface of the periotic, the absence of a groove on the lateral face of the periotic extending onto the posterior process, and the rounded manubrium of the malleus. Other cranial features that differentiate E. langewieschei include the following: a slit-like for- amen present in the anterior portion of the periotic fossa (1⁄4 subcircular fossa), the absence of a narrow cleft in the premaxilla at the vertex, and the limited expansion of the pterygoid and pterygoid sinus fossa anteriorly and dorsally. |