Brevirostruavis macrohyoideus gen. et sp. nov. (1 Viewer)

[Fred Ruhe]

Zhiheng Li, Min Wang, Thonmas A. Stidham, Zhonghe Zhou & Julia Clarke, in press

Novel evolution of a hyper-elongated tongue in a Cretaceous enantiornithine from China and the evolution of the hyolingual apparatus and feeding in birds

Journal of Anatomy. in press.
doi:10.1111/joa.13588

Abstract: https://onlinelibrary.wiley.com/doi/10.1111/joa.13588

The globally distributed extinct clade Enantiornithes comprises the most diverse early radiation of birds in the Mesozoic with species exhibiting a wide range of body sizes, morphologies, and ecologies. The fossil of a new enantiornithine bird, Brevirostruavis macrohyoideus gen. et sp. nov., from the Lower Cretaceous Jiufotang Formation in Liaoning Province, northeastern China, preserves a few important skeletal features previously unknown among early stem and extant birds, including an extremely elongate bony hyoid element (only slightly shorter than the skull), combined with a short cranial rostrum. The long hyoid provides direct evidence for the evolution of specialized feeding in this extinct species, and appears similar to the highly mobile tongue that is mobilized by the paired epibranchials present in living hummingbirds, honeyeaters, and woodpeckers. The likely linkage between food acquisition and tongue protrusion might have been a key factor in the independent evolution of particularly elongate hyobranchials in early birds.

Enjoy,

Fred

 

[Fred Ruhe]

SYSTEMATIC PALEONTOLOGY

Aves Linnaeus, 1758.
Enantiornithes Walker, 1981.
Brevirostruavis macrohyoideus gen. et sp. nov.

Holotype
IVPP (Institute of Vertebrate Paleontology and Paleoanthropology,
Beijing, China) V13266 is a nearly complete skeleton preserved on
a single slab (missing part of the humerus and the pelvic elements),
with associated traces of preserved integument around the body

Etymology
The genus name refers to its short rostrum (and bird), and the specific
epithet refers to the particularly long hyoid apparatus.

Locality and horizon
Xiaotaizi Village, Jianchang County, Liaoning Province, China;
Jiufotang Formation, Lower Cretaceous. Age approximately 120 Ma
(He et al., 2004).

Diagnosis
A medium-sized enantiornithine that is distinguished from all known
enantiornithines based on the unique combination of the following
features: a short and pointed skull rostrum lined with small peg-shaped
teeth; a pair of extremely long ceratobranchials, only slightly shorter than the skull length (see Table 1); a sternum with well-extended craniolateral processes; lateral trabeculae of the sternum with expanded triangular processes at the caudal ends; elongate prezygapophyses of the cranial cervical vertebrae; postzygapophyseal facet of the axis is tear-drop shaped; third cervical vertebra with sub-rounded articular facet of the postzygapophyses; ischium bearing
a pronounced proximodorsal process; distal tibiotarsus with a knob on its cranial surface; length ratio between the fibula and tibiotarsus approximately 0.7; tarsometatarsus about half of the length of the tibiotarsus; medial rim of metatarsal trochlea III larger than the lateral rim; and pedal digit-Imore robust than other pedal digits.

Fred


F I G U R E 1 Photograph and line drawing of the body of the holotype specimen of Brevirostruavis macrohyoideus (IVPP V13266).
Anatomical abbreviations: c, coracoid; cav, caudal vertebrate; cv, cervical; fe, femur; fi, fibula; fu, furcula; h, humerus; il, ilium; isch, ischium; int, integument; mc I, alular metacarpal; mc II, major metacarpal; pub, pubis; py, pygostyle; r, radius; ra, radiale; sk, skull; st, sternum; tbt, tibiotarsus; tv, thoracic vertebrate; tmt, tarsometatarsus; u, ulna; and ul, lnare.

F I G U R E 2 Photograph and line drawing of the skull of the holotype specimen of Brevirostruavis macrohyoideus (IVPP V13266). Anatomical
abbreviations: an, angular; ar, articular; at, atlas; ax, axis; bp, basisphenoid process; bs, basisphenoid; cb, ceratobranchial; cr, cervical rib; cv, cervical; de, dentary; dr, descending ramus; ep?, ectopterygoid?; fr, frontal; la, lacrimal; ju, jugal; ma, maxillae; na, nasal; op, occipital process; pa, parietal; pm, premaxilla; pt?, pterygoid?; qu, quadrate; sa, surangular; and to, tooth.

F I G U R E 3 Phylogenetic position of Brevirostruavis macrohyoideus (IVPP V 13266) in Avialae. (a) Strict consensus tree from current
phylogenetic analysis; (b) reduced consensus tree with ten most unstable taxa removed. The bootstrap and absolute Bremer support values are denoted in normal and bold Italic fonts.