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Gnathomortis
Taxonomy
Gnathomortis was named by Lively (2020). Its type is Prognathodon stadtmani.
It was assigned to Mosasaurinae by Lively (2020).
It was assigned to Mosasaurinae by Lively (2020).
Species
Synonymy list
Year | Name and author |
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2020 | Gnathomortis Lively p. 15 |
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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 | |
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J. R. Lively 2020 | Gnathomortis stadtmani is diagnosed from all other mosasaurines by the following unique combination of characters and autapomorphies (denoted by an *): a small pre- dental rostrum that resembles those of Prognathodon spp., differ- ing from the long, pointed rostrum of early-diverging mosasaurines such as Clidastes propython and the inflated, rec- tangular rostrum of Plesiotylosaurus crassidens; 13 tooth positions in the maxilla, as in Prognathodon kianda, Prognathodon overtoni, Globidens dakotensis, and Eremiasaurus heterodontus; a premaxilla-maxilla suture that ends dorsal to the fourth tooth position, as in Globidens dakotensis and some early-diverging mosasaurines, differing from the shorter suture observed in Prognathodon overtoni; shallow excavation of the dorsal maxilla by the external naris, differing from the deeper emargina- tion exhibited by Prognathodon spp. and early-diverging mosa- saurines and the lack of emargination exhibited by Mosasaurus spp. and Plesiotylosaurus crassidens; pterygoid tooth crowns that are smaller than the marginal dentition, differing from members of Prognathodon spp.; posteromedial margin of the frontal and pineal foramen separated by a distance narrower than the length of the foramen, as in Globidens dakotensis, Plesiotylosaurus crassidens, and Mosasaurus spp.; contact between the prefrontal and postorbitofrontal on the ventral surface of the frontal, as in Prognathodon spp., Globidens spp., Mosasaurus spp., Plotosaurus bennisoni, Plesiotylosaurus crassidens, and Eremiasaurus heterodontus; straight anterodorsal margin of the suprastapedial process, differing from the curved margin in other described mosasaurines*; a suprastapedial process of the quadrate that is half as tall as the total height of the element; a narrow separation between the ascending tympanic rim and the suprastapedial process*, lacking the fusion of those two structures seen in Prognathodon, Globidens, Eremiasaurus, and Plesiotylosaurus; an infrastapedial process represented by a small swelling ventral to the stapedial notch as in Clidastes propython; a dorsoventrally expanded quadrate shaft ventral to the tympanic ala, greater than 50% the height of the ala, as in Prognathodon, Globidens, and Plesiotylosaurus; a prominent anterodorsal projection of the mandibular condyle, as in Clidastes propython; 14 tooth positions in the dentary*; medial inflection of the retroarticular process almost into the horizontal plane, as in Mosasaurus, Plotosaurus, Prognathodon, and Globidens; concave ventral margin of the atlantal synapo- physes, as in other mosasaurines except Mosasaurus spp. Gnathomortis stadtmani is currently the oldest known mosasaur- ine with a skull longer than 1 m. |
Measurements
No measurements are available
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Source: f = family, c = class, subp = subphylum, uc = unranked clade | |||||
References: Gervais 1852, Carroll 1988, Hendy et al. 2009 |
Age range: Middle Campanian or 83.50000 to 70.60000 Ma
Collections: one only
Time interval | Ma | Country or state | Original ID and collection number |
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Middle Campanian | USA (Colorado) | Prognathodon stadtmani (5607) |