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Nahmavis grandei, gen. et sp. nov. (1 Viewer)

Fred Ruhe

Well-known member
Netherlands
Grace Musser & Julia A. Clarke, 2020

An exceptionally preserved specimen from the Green River Formation elucidates complex phenotypic evolution in Gruiformes and Charadriiformes

Frontiers in Ecology and Evolution. 8: Article 559929. doi:10.3389/fevo.2020.559929

Free pdf: https://sci-hub.do/10.3389/fevo.2020.559929

Abstract: https://www.frontiersin.org/articles/10.3389/fevo.2020.559929/full

The stem lineage relationships and early phenotypic evolution of Charadriiformes (shorebirds) and Gruiformes (rails, cranes, and allies) remain unresolved. It is still debated whether these clades are sister-taxa. New phylogenetic analyses incorporating Paleogene fossils have the potential to reveal the evolutionary connections of these two speciose and evolutionarily critical neoavian subclades. Although Gruiformes have a rich Paleogene fossil record, most of these fossils have not been robustly placed. The Paleogene fossil record of Charadriiformes is scarce and largely consists of fragmentary single elements. Only one proposed Eocene charadriiform-like taxon, Scandiavis mikkelseni of Denmark, is represented by a partial skeleton. Here, we describe a new species from the early Eocene Green River Formation of North America comprising a partial skeleton and feather remains. Because the skeleton lacks the pectoral girdle and forelimbs as in S. mikkelseni, only features of the skull, axial skeleton, and hind limb are available to resolve the phylogenetic placement of this taxon. These anatomical subregions initially showed features seen in Charadriiformes and Gruiformes. To assess placement of this taxon, we use a matrix consisting of 693 morphological characters and 60 taxa, including S. mikkelseni and the oldest known charadriiform taxa represented by single elements. These more fragmentary records comprise two distal humeri from the earliest Eocene Naranbulag Formation of Mongolia and the early Eocene Nanjemoy Formation of Virginia. Our phylogenetic analyses recover the new taxon and S. mikkelseni alternatively as a charadriiform or as a stem-gruiform; placement is contingent upon enforced relationships for major neoavian subclades recovered by recent molecular-based phylogenies. Specifically, when constraint trees based on results that do not recover Charadriiformes and Gruiformes as sister-taxa are used, the new taxon and S. mikkelseni are recovered within stem Gruiformes. Both Paleogene fossil humeri are consistently recovered within crown Charadriiformes. If placement of these humeri or the new taxon as charadriiforms are correct, this may indicate that recent divergence time analyses have underestimated the crown age of another major crown avian subclade; however, more complete sampling of these taxa is necessary, especially of more complete specimens with pectoral elements.

Enjoy,

Fred
 

l_raty

laurent raty
Now, that's an interesting case...
The paper is registered in ZooBank, and the registration info is given in the "provisional pdf" (first link above), which however "does not constitute published work" in the sense of the Code (ICZN 9) because "preliminary versions of works accessible electronically in advance of publication" (which this file clearly is) are excluded by ICZN 9.9.
Zoobank Identifier: urn:lsid:zoobank.org:pub:57238342-B0D2-4764-8F6C-79205EB14F1A
Genus: urn:lsid:zoobank.org:act: 8B1CD8D4-6C0F-4535-B1B2-C87286D6234B
Species: urn:lsid:zoobank.org:act:7E917BC1-DCC7-4046-B7FE-14A9537E2F06
But the data was apparently deleted in the final editorial process, and is not present in the final version (second link)... Which is thus not validly published either, because it does not "contain evidence in the work itself that such registration has occurred", as required by ICZN 8.5.3.
 

Fred Ruhe

Well-known member
Netherlands
Systematic Paleontology

AVES (Linnaeus, 1758),
NEOGNATHAE (Pycraft, 1900),
Neoaves (Sibley et al., 1988),
Nahmavis grandei gen. et sp. nov.

Holotype Specimen

FMNH PA778, a partial skeleton with feathers and tracheal rings preserved within a kerogen-rich laminated micrite slab. Remains of the sternum, pectoral girdle and forelimb are absent.

Etymology

Nahmavis is Native American in origin (Nahma, used by the Shoshoni Great Basin tribe indigenous to this region) and means “together” or “of two things” (Shoshoni Language Project, 2018). The name references the combination of features in this new taxon. The species honors Dr. Lance Grande, who collected the holotype specimen, in recognition of his premier and extensive research on the Green River Formation.

Type Locality and Horizon

The holotype specimen was collected from Fossil Butte Member (sensu Buchheim, 1994) Locality A (F-1 A in Grande and Buchheim, 1994; Grande, 2013), located in SE¼, SE¼, Sec. 19, T.21N., R.117W., and NE¼, NE¼, Sec. 30, T.21N., R117W., Kemmerer 15 min Quadrangle (USGS). FBM Locality A is a mid-lake locality and is within a 30−40 cm thick horizon representing roughly a few 100 years of the early Eocene (Grande and Buchheim, 1994). The mid-lake fossil-bearing, laminated micrite facies are made up of thin calcite laminae that alternate with almost pure kerogen (Grande and Buchheim, 1994). Few other bird skeletons have been recovered from the mid-lake locality, with the majority being recovered from the near-shore deposits of FBM locality H (F-2 A in Grande and Buchheim, 1994; Grande, 2013). The mid-lake locality is additionally characterized by a sharp decrease in benthic fauna, perhaps suggesting that bottom conditions were primarily anoxic or dysaerobic as in the avian fossil-bearing deposits of the Fur Formation (Pedersen and Surlyk, 1983; Bertelli et al., 2010).

Diagnosis

Nahmavis grandei is diagnosed by a proposed unique combination of characters comprising (1) holorhinal nares rostral to the zona flexoria craniofacialis (Figures 1, 2, 6A), (2) a prominent, dorsally protruding crest-like orbital margin (Figures 1, 2, com; see Musser and Cracraft, 2019), (3) a quadrate with apneumatic, well-separated heads (Figures 2, 3A–C, 6D,E), (4) a quadrate with a prominent crista lateralis (Figures 3B,C,L, 6E), (5) a prominent crista tympanica of the quadrate that terminates ventrally within the ventral half of the otic process (Figures 3A,C, ct), (6) a caudally concave otic process of the quadrate (Figures 3C, 6D), (7) a caudal condyle that is confluent with the lateral condyle (Figures 3C,L, 6D), (8) absence of a notarium (Figure 1), (9) preacetabular ilia that are unfused to the synsacrum (Figure 1, ili and Figure 6H), (10) an elongate, thin and recurved pubis (Figure 1, pub) (11) a femur that is over half the length of the tibiotarsus (Figure 1, fem), (12) a prominent crista cnemialis cranialis of the tibiotarsus that is proximally projected above the fossa retropatellares (Figure 3E, ccc), (13) a tarsometatarsus that approximately half the length of the tibiotarsus (Figure 1, tmt), (14) a medial hypotarsal crest that is projected farther plantar than the lateral crest (Figures 3J–L, crm), (15) a deep sulcus extensorius of the tarsometatarsus (Figures 3J,K, ext), (16) plantar alae present on metatarsal trochleae IV and II (Figures 3J–L), (17) an unbowed pedal digit I: phalanx 1 that is about half the length of pedal digit III:1 (Figures 3J–L, I:1), (18) a lack of a plantomedial flange on proximal margin of pedal digit IV:1 (Figures 3J–L), and (19) a pedal digit IV:4 that is more elongate than pedal digit IV:3 (Figure 3L). Diagnosis for the genus as per the species.

Differential Diagnosis

Nahmavis grandei can be distinguished from earliest Eocene Scandiavis mikkelseni Bertelli et al. (2013) due to possessing (1) less rostrocaudally and dorsoventrally extensive nares (Figures 1, 2), (2) a more acute antorbital angle of approximately 45° (Figure 2, ant), (3) a more caudally elongated cranium (Figures 1, 2), (4) a ventrally oriented postorbital process (Figure 2, porb), (5) a less cranially projected crista cnemialis cranialis of the tibiotarsus (Figures 3D,E, ccc), (6) a crista cnemialis cranialis with a more acuminate distal apex than that of S. mikkelseni (Figures 3D,E; apx), (7) a lack of a notch along the distal rim of the medial condyle of the tibiotarsus (Figures 3G,H), (8) a deeper fossa parahypotarsalis lateralis in the tarsometatarsus (Figure 3L, phl), and (9) a longer femur and tibiotarsus (Figure 1, fem and tbt; Table 2). N. grandei is differentiated from the charadriiform-like Morsoravis sedilis Bertelli et al. (2010) due to the presence of a zygodactyl foot in the latter taxon. Presence of this condition is suggested in the holotype due to a wide proximal phalanx of the fourth toe (Mayr, 2011a), and this taxon was recently phylogenetically placed within Pan-Passeriformes (Ksepka et al., 2019). N. grandei is distinguished from Salmila robusta due to possessing (1) a less decurved and less raptorial anterior terminus of the premaxilla (Figures 1, 2, prx), (2) a more caudally elongate cranium (Figures 1, 2), (3) a truncate postorbital process (Figure 2, porb), (4) a straight and dorsally oriented symphysis of the mandible that is not recurved (Figure 2, sym), (5) a decurved mandibular ramus rostral to the coronoid process (Figure 2, ram), (6) a half-moon shaped pygostyle with a caudal apex that deviates ventrally from the major axis of the pygostyle (Figure 1, pyg), (7) a more elongate pygostyle, (8) a more elongate pubis with at least ¼of the pubis extending caudally beyond the caudal margin of the ischium (Figure 1, pub), (9) a femur that is over half the length of the tibiotarsus (Figure 1, fem), (10) a lateral condyle of the tibiotarsus that is more proximally located than the medial condyle (Figures 3G,H), (11) a deep fossa parahypotarsalis lateralis of the tarsometatarsus (Figure 3L, phl), (12) a metatarsal II trochlea with a plantarly prominent ala (Figures 1, 3J–L, mtII), (13) a metatarsal IV trochlea that is more distally extensive then the metatarsal II trochlea (Figures 3J–L, mtIV), (14) a pedal digit I: phalanx 1 that is approximately half the length of digit III: phalanx 1 (Figures 1, 3, I:1), and (15) a lack of a medially protruding flange at the proximal margin of digit IV: phalanx 1 (Figure 1, IV, see also CT, data in Supplementary Material).

Fred

Figure 1. Photograph (A) and line drawing (B) of FMNH PA778. Bone is unfilled, matrix is gray, cartilaginous tracheal and possible syringeal rings are shown in light gray, and feathers and other unidentifiable soft tissue is displayed in dark gray. Extremely crushed bone and bone margin is delimited with dashed margins. Anatomical abbreviations: prx, premaxilla; com, crest-like orbital margin; scl, scleral rings; qdr, quadrate; mnd, mandible; jug, jugal; hyd hyoid; cvt, cervical vertebrae; cpr, costal processes; thv, thoracic vertebra; cdv, caudal vertebra; pub, pubis; pyg, pygostyle; rib, ribs; unc, uncinate process; ili, preacetabular ilium; isch, postacetabular ischium; pub, pubis; fem, femur; tbt, tibiotarsus; tmt, tarsometatarsus; mtII, trochlea metatarsal II; mtIII, trochlea metatarsal III; mtI, metatarsal I; I:1, hallux; II:1, phalanx one of digit II; III:1, phalanx one of digit III; IV:1, phalanx one of digit IV; clw, claw; thr, tracheal rings.

Figure 2. Strict consensus tree of 56 MPTs of 5,248 steps recovered using the most recent Kimball et al. (2019) tree as a molecular backbone constraint (CI = 0.163, RI = 0.462, RC = 0.075, HI = 0.838). Charadriiform, gruoid and ralloid silhouettes are placed at the crowns of their respective clades. Charadriiformes are highlighted in blue, Gruiformes are highlighted in red, and violet spans the possible phylogenetic placements of Nahmavis grandei across these clades. All extinct taxa are denoted with daggers. Bootstrap support values greater than 50% are denoted above branches.
 

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l_raty

laurent raty
The paper is registered in ZooBank, and the registration info is given in the "provisional pdf" (first link above), which however "does not constitute published work" in the sense of the Code (ICZN 9) because "preliminary versions of works accessible electronically in advance of publication" (which this file clearly is) are excluded by ICZN 9.9.

But the data was apparently deleted in the final editorial process, and is not present in the final version (second link)... Which is thus not validly published either, because it does not "contain evidence in the work itself that such registration has occurred", as required by ICZN 8.5.3.
Update --
The currently available pdf has the ZooBank registration data restored in it. As this registration had not been used to make an earlier version published, I guess the work can be regarded as published in this form.
However, the date of publication stated in the pdf is still 26 Oct 2020, and this is certainly not correct. (It's the date of issuance of the article without the registration data, which was not published in the sense of the Code.) The metadata of the current pdf indicate that it was created and last modified on 4 Dec 2020.
 

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