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Xenorophidae
Taxonomy
Xenorophidae was named by Uhen (2008) [Xenorophidae was used by Luo & Gingerich (1999) and Marino et al (2004) with no diagnosis; Xenorophiidae was used by Fordyce (2003) and Bianucci and Landini (2007) with no diagnosis.]. It was considered monophyletic by Uhen (2008) and Sanders and Geisler (2015).
It was assigned to Odontoceti by Sanders and Geisler (2015) and Churchill et al. (2016); and to Odontoceti by Uhen (2008), Rice (2009), Geisler et al. (2011), Geisler et al. (2014), Marx et al. (2016), Boessenecker et al. (2017), Berta (2017) and Boessenecker and Geisler (2023).
It was assigned to Odontoceti by Sanders and Geisler (2015) and Churchill et al. (2016); and to Odontoceti by Uhen (2008), Rice (2009), Geisler et al. (2011), Geisler et al. (2014), Marx et al. (2016), Boessenecker et al. (2017), Berta (2017) and Boessenecker and Geisler (2023).
Synonymy list
| Year | Name and author |
|---|---|
| 2008 | Xenorophidae Uhen p. 434 |
| 2009 | Xenorophidae Rice p. 235 figs. Table 1 |
| 2011 | Xenorophidae Geisler et al. p. 5 figs. Table 1 |
| 2014 | Xenorophidae Geisler et al. |
| 2015 | Xenorophidae Sanders and Geisler p. 2 |
| 2016 | Xenorophidae Churchill et al. p. 1 |
| 2016 | Xenorophidae Marx et al. p. 115 |
| 2017 | Xenorophidae Berta p. 160 |
| 2017 | Xenorophidae Boessenecker et al. p. 4 |
| 2023 | Xenorophidae Boessenecker and Geisler p. 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.
Fm. †Xenorophidae Uhen 2008
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G. †Xenorophus Kellogg 1923
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†Xenorophus simplicidens Boessenecker and Geisler 2023
†Xenorophus sloanii Kellogg 1923
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| M. D. Uhen 2008 | Geisler & Sanders (2003) list the following synapomorphies: base of the rostrum transversely narrow (compared to the width of the skull across the orbits), maxillae wedged between palatines, anterior edge of the supraorbital process directed anterolaterally, maxilla and palatine and/or pterygoid form ventromedial edge of internal infraorbital foramen, lateral tuberosity of petrosal (periotic) elongate and narrow separation of crista parotica and caudal tympanic pro- cess of petrosal (periotic). In addition to these characteristics, both Xenorophus and Albertocetus (new genus, named below) have greatly expanded lacrimals. In both genera, the lacrimal forms the anterior border of the orbit and extends posteriorly, dorsally covering the frontal over most of the lateral margin of the supraorbital process of the frontal. Archaeodelphis has a somewhat enlarged lacrimal, but not nearly as enlarged as in Xenorophus and Albertocetus. | |
| A. E. Sanders and J. H. Geisler 2015 | The only known clade of cetaceans in which the premaxilla—instead of the maxilla—articulates with the frontal along most of its entire anteroposterior extent and extends laterally across the medial half of the supraorbital pro- cess of the frontal beneath the maxilla (Fig. 3A). The premaxilla bears a prominent crest that is lateral to the nasal opening and nasal bone and that is overlain by a thin layer of the maxilla on its lateral side; the lacrimal covers most of the dorsal surface of the lateral portion of the supraorbital process of the frontal; the maxilla is deeply excavated adjacent to the antorbital notch, forming an ovoid basin to which we here apply the term antorbi- tal fossa (Fig. 3A). Formerly this structure had been referred to as the rostral basin (Geisler and Sanders, 2003), but we here introduce a new term to indicate the differences in morphology between these depressions in ziphiids and xenorophids. Ven- trally, the maxilla and/or premaxilla is visible through a broad circular opening—here termed the ‘frontal window’—in the supraorbital portion of the frontal bone. The frontal window is visible in the holotype of X. sloanii (Fig. 3C), although the ante- rior margin of the window is damaged and the posterior margin is not preserved. Although the facial and orbital parts of the skull are highly telescoped, the parietals in xenorophids form most of the dorsal and lateral portions of the braincase as in typical land mammals, and there is a sagittal crest (Whitmore and Sanders, 1977:fig. 1; Uhen, 2008:fig. 2). | |
| R. W. Boessenecker and J. H. Geisler 2023 | Xenorophidae is diagnosed nine synapomorphies, including ventral exposure of lacrimal and jugal being intermediate in size (80:1), posterior border of supraorbital process extending posteromedially from its lateral end (85:0), lateral side of postorbital process facing laterally instead of dorsolaterally (89:1), premaxillae dorsally separated by a gap that is between 32% and 56% the width of the external nares (94:1), premaxilla expanded laterally over the supraorbital process of the frontal and lying between that bone and the maxilla (106:1), premaxilla terminating over the posterior half of orbit (107:3), anterior edge of nasal terminating over anterior half of orbit (114:4), pachyostosis of premaxilla (125:1), and basioccipital crests forming a 45–68◦ angle (240:2). Character 106 is the basis of the definition of this family, and also shows no homoplasy on our most parsimonious trees. Similarly, character 85 state 0 and character 125 state 1 have only evolved once. The other character states evolved convergently in non-xenorophids as follows: character 80 state 1 occurs in ChM PV2761, PV4802, Agorophius pygmaeus, Squalodon calvertensis, and most crown odontocetes; character 89 state 1 also occurs in many crown odontocetes; character 94 state 1 occurs in Phoberodon arctirostris and most crown odontocetes; character 107 state 3 occurs in several Oligocene odontocetes including ChM PV5852, Simocetus rayi, and Papahu taitapu; character 114 state 4 also occurs in ChM PV5852, PV4178, and Ankylorhiza; and character 240 state 2 also occurs in Simocetus rayi, Ankylorhiza tiedemani, Waipatia maerewhenua, Papahu taitapu, and Ediscetus osbornei. All xenorophids, except for the unnamed taxon represented by ChM PV4746, are also characterized by the following derived characters, including lacrimal expanded dorsally and posteriorly over the supraorbital process of the frontal, lateral to the maxilla and premaxilla (76:2); presence of bilateral antorbital basins (92:1); ventral window in supraorbital process of frontal that exposes overlying maxilla and premaxilla (174:1); and posterior end of premaxilla widening abruptly (390:3). Xenorophids are also characterized by the following plesiomorphic characters, which are atypical of odontocetes, including a flat palate (but not ChM PV4746), absence of a dorsal infraorbital foramen on the supraorbital process, absence of an inflection of the premaxilla that separates a posteromedial splint from a posterolateral plate (but not in ChM PV4746), supraoccipital alone forming the vertex (but not in ChM PV4746), alisphenoid/squamosal suture is positioned anterior to foramen ovale, and lateral side of periotic having a sulcus for the capsuloparietal vein. |
Measurements
No measurements are available
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| Source: subo = suborder, o = order | |||||
| Reference: Uhen 2004 | |||||
Age range: base of the Late/Upper Oligocene to the top of the Chattian or 28.40000 to 23.03000 Ma
Collections (19 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Rupelian | USA (South Carolina) | Albertocetus meffordorum (189779) Albertocetus sp. (206951) Ashleycetus planicapitis (165736) Inermorostrum xenops (186670) Xenorophus sloani (229945) Xenorophus sloanii (45500 232432 232433) Xenorophus sp. (45777) Xenorophus sp., Albertocetus meffordorum (188100) | |
| Rupelian | Azerbaijan | Microzeuglodon caucasicum (45740) | |
| Late/Upper Oligocene | USA (North Carolina) | Albertocetus meffordorum, Echovenator sp. (71651) | |
| Chattian | USA (South Carolina) | Archaeodelphis patrius (68974) Cotylocara macei (154905) Echovenator sandersi (180866) Xenorophus simplicidens (229963 232431) Xenorophus sp. (112635) | |
| Chattian | USA (North Carolina) | Xenorophidae indet., Albertocetus meffordorum (54075) |