Blutwurstia oliviae, Smith & Bhullar & Bloch, 2022

Smith, Krister T., Bhullar, Bhart-Anjan S. & Bloch, Jonathan I., 2022, New diminutive Eocene lizard reveals high K-Pg survivorship and taxonomic diversity of stem xenosaurs in North America, American Museum Novitates 2022 (3986), pp. 1-36 : 23-25

Blutwurstia oliviae , new species

Figures 2–6

This nomenclatural act has been registered in ZooBank, urn:lsid:zoobank.org:act:261DB1A7-F9CB-4FE2-BC86-58B3DBA2B0EE

HOLOTYPE: USNM PAL 768729 (nearly complete left maxilla, left palpebral, left jugal, postdentary portion of left mandible, dorsal vertebra, presumably from a single individual).

HORIZON AND LOCALITY: 8abc Limestone, lower Eocene Willwood Formation, Wyoming.

DISTRIBUTION: Known only from type locality.

ETYMOLOGY: The made-up word “oliviae” is considered a noun in apposition (ICZN Article 31). Any similarity to the given name of O. Rieppel, whose contributions to our understanding of anguimorph lizards rank scarcely less than his contributions to philosophy of systematics, is purely coincidental. Such an honor might be seen as unctuous, olivaria (Latin, “of olives, olive oil”).

DIAGNOSIS: Anguimorph lizard with trenchant, unicuspid, unstriated teeth lacking plicidentine. Shares with Xenosaurus (and other pan-xenosaurs, in which they are known) the following apomorphies: posterior portion of nasal facet of maxilla folded towards the vertical; palpebral shaped like equilateral triangle with short, blunt posterolateral process; foramen in jugal adductor surface; and dorsal vertebrae with very short neural spine and depressed centrum. Primitive with respect to Restes , Exostinus spp. , and Xenosaurus in the following characters: teeth unicuspid, anterior end of lacrimal recess of maxilla more anterior, maxilla supradental thickening weak, and palpebral medial margin without S-curve. Shares with Entomophontes spp. the following apomorphies: increased length and reduced height of the facial process of the maxilla, increase in tooth diameter posteriorly in tooth row, and strong mesial and distal carinae on cheek teeth. Autapomorphies are its small size (SVL about 5 cm) and poor development of the osteodermal crust on facial process of the maxilla in ontogenetically advanced individuals.

COMMENTS: While monophyly of Entomophontes with respect to Blutwurstia is neither supported nor rejected by our phylogenetic analyses, the two differ in a significant character not covered by the data matrix, namely the presence of a thick osteodermal crust (on the maxilla, at least; the frontal and parietal being unknown in B. oliviae and E. hutchisoni ). As more of B. oliviae and Entomophontes spp. are discovered, it may become clear that recognition of Blutwurstia renders Entomophontes paraphyletic, in which case the former should be synonymized.

C. FBD - no sampled ancestors D. FBD - sampled ancestors

El. multicarinata

X.newmanorum

X.platyceps

X.agrenon

X.rectocollaris

X.rackhami

X.grandis

Figures

FIG. 2. Nearly complete left maxilla of USNM PAL 768729. A, lateral and B, medial views. Medial view also shows the palpebral, which remained attached to the maxilla.C, Close-up of third (preserved) maxillary tooth from rear. Abbreviations: ASAF, anterior superior alveolar foramen; cr.tv., crista transversalis; fac.pr., facial process; j.gr., jugal groove; l.fac., lacrimal facet; lat.r., lateral ridge (= crista lateralis); l.rec., lacrimal recess; n.fac., nasal facet; palp., palpebral; prf.rec., prefrontal recess.

FIG. 3. Right jugal of USNM PAL 768729. A, lateral and B, medial views. Abbreviations: mx.fac., maxillary facet; qj.tub., quadratojugal tubercle.

FIG. 4. Partial left mandible of USNM PAL 768729 in medial view. A, Articular region, with broken retroarticular process. B, Middle region, including coronoid and angular. Abbreviations: ang., angular; cb.I, ceratobranchial I; cn., coronoid; part., prearticular; p.mh.f., posterior mylohyoid foramen; ra.pr., retroarticular process; spl.fac., splenial facet.

FIG. 5. Dorsal vertebra of USNM PAL 768729. A, dorsal, B, left lateral, and C, ventral views. Note the low neural spine. Abbreviations: cond., condyle; cot., cotyle; n.sp., neural spine; poz., postzygapophysis; prz., prezygapophysis; syn., synapophysis.

FIG. 6. Central fragment of left scapulocoracoid of USNM PAL 768729. The scapula and coracoid are indistinguishably fused. Abbreviations: cc.for., coracoid foramen; gl.fos., glenoid fossa; sc-cc.fen., scapulocoracoid fenestra; sc.for., scapular foramen.