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Taxonomy
Dagonodum was named by Ramassamy (2016). Its type is Dagonodum mojnum.
It was assigned to Ziphiidae by Ramassamy (2016) and Berta (2017).
It was assigned to Ziphiidae by Ramassamy (2016) and Berta (2017).
Species
D. mojnum (type species)
Synonymy list
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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.
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| B. Ramassamy 2016 | Dagonodum mojnum is a medium-sized ziphiid with an elongated rostrum (approximately 70% of the total condylobasal length). It differs from all odontocetes except ziphiids in having the vertex bearing a strong premaxillary crest; the enlargement of the apical mandibular tooth, and the reduction of the dorsal keel on the posterior process of the periotic.
It shares with Anoplonossa forcipata and Berardius the presence of a pair of apical and subapical tusks; with the genera Messapicetus and Ziphirostrum the medial fusion of the premaxillae dorsal to the mesorostral groove on the rostrum anterior to the premaxillary sac fossae; and with Aporotus, Beneziphius, Messapicetus and Ziphirostrum the pres- ence of a prenarial basin laterally margined by the maxilla. Dagonodum mojnum differs from all other Ziphiidae based on the following unique combination of characters: nasal anteroposteriorly elongated and trapezoid in dorsal view; left nasal projecting into the frontal posteromedially; presence of a triangular depression on the anteroventral surface of the pars cochlearis; Eustachian outlet approximately level with the dorsalmost margin of the posterior portion of the involucrum in medial view; presence of an incipient anterior spine on the tympanic bulla; and presence of two anterodorsally directed pairs of mandibular tusks. It further differs from all Berardiinae in having a moderate transverse constriction in the ascending process of the premaxilla, a larger premaxillary crest equivalent in transverse width to the nasal and in lacking a posterior rounded protuberance formed by the frontals and/or interparietal on the vertex; from the Hyperoodontinae in the lack of a deep anteromedial excavation of the nasals; and from the Ziphiinae in the lack of a premaxillary sac fossa overhanging the maxilla laterally. Dagonodum mojnum differs from Globicetus hiberus, Imocetus piscatus and the genus Tusciziphius in lacking an extreme ossification and fusion of the bones on the trapezoidal vertex and the absence of a dorsal prominence on the premaxillae along the rostrum (not present in I. piscatus); from Nenga meganasalis and Xhosacetus hendeyesi in having a narrower nasal not occupying most of the vertex; from Pterocetus benguelae in having a shallower antorbital notch with a less developed preor- bital process; from Tasmacetus shepherdi in having the premaxillary crest anterolaterally orientated and the external surface of the nasal facing dorsally, not progressively sloping ventrally; from Aporotus dicyrtus, A. recuvirostris, Beneziphius brevirostris and Ziphirostrum marginatum in lacking a strong thick- ening of the maxilla at the base of the rostrum and in having a prominential notch (condition unknown in Beneziphius); from Aporotus in having the premaxillae dorsally roofing the mesorostral groove fused; and from Beneziphius in lacking the extension of the medial fusion of the premaxillae more posteriorly until the premaxillary sac fossae. Dagonodum mojnum differs from Messapicetus in having a less pronounced transverse constriction in the ascending process of the premaxilla characterized by U-shaped margins (ratio between transverse width of the premaxillary crest and minimum trans- verse width of the ascending process equals 0.72); an anteroposteriorly longer nasal as wide as long (ratio between median length and total width equals 0.53); and a posteromedial projection of the nasal into the frontal and in lacking transversely compressed alveoli. |