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Crosnoornis nargizia gen. et sp. nov. (1 Viewer)

Fred Ruhe

Well-known member
Netherlands
Zbigniew M. Bochenski, Teresa Tomek, Małgorzata Bujoczek & Grzegorz Salwa, 2021

A new passeriform (Aves: Passeriformes) from the early Oligocene of Poland sheds light on the beginnings of Suboscines.

Journal of Ornithology. in press.
doi:10.1007/s10336-021-01858-0

Abstract and free pdf: https://link.springer.com/article/10.1007/s10336-021-01858-0

The paper describes a complete specimen of a passerine bird from the early Oligocene of Poland, preserved as imprints of bones and feathers on two slabs. Crosnoornis nargizia gen. et sp. nov. is just the fifth passerine species described from the Paleogene worldwide and the fourth complete. The features preserved in the distal elements of the wing exclude Acanthisittidae and Oscines and indicate that this bird can be included in Suboscines, making it the second complete representative of this group in the Paleogene. A strong, straight beak indicates that this bird could feed on a variety of foods, including hard seeds, fruit and invertebrates, and, therefore, occupied a different foraging niche than the Oligocene passerines described so far. The wing proportions, a very short tail and relatively long legs indicate that this bird spent most of its time in the forest, close to the ground in dense shrubs or dense tree crowns.

Enjoy,

Fred
 
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Fred Ruhe

Well-known member
Netherlands
Systematic paleontology

Aves Linnaeus 1758
Passeriformes Linnaeus 1758
Suboscines (sensu Ericson et al. 2003)
Family indeterminate
Genus Crosnoornis gen. nov.
Type species Crosnoornis nargizia sp. nov.

Etymology: The genus name Crosno is the Latin equivalent of the Polish Krosno, a town located nearby the type locality, Rudawka Rymanowska, added to the Ancient Greek ὄρνις (ornis) meaning “bird”.

Remarks: The specimen shows derived features typical of Passeriformes, to which it is also morphologically similar. In particular, the sternum bears (1) bifurcated spina externa and (2) a single pair of incisions in the caudal end; the humerus has (3) a prominent processus flexorius that protrudes distally; the ulna bears (4) a prominent olecranon separated from the shaft by a shallow saddle; (5) the radius has a short proximo-distally facies articularis ulnaris; the carpometacarpus bears (6) a long and narrow spatium intermetacarpale, (7) processus intermetacarpalis, and os metacarpale minus with (8) a narrow distal end that (9) protrudes a little farther distally than os metacarpale majus; phalanx proximalis digiti majoris (10) short, broad and cleaver-shaped, and (11) with a distally directed protrusion in the posterior part of its distal edge; the tarsometatarsus bears (12) a hypotarsus which is short proximo-distally, (13) a prominent crista plantaris lateralis that runs along the shaft, and (14) trochleae of the second, third and fourth toes arranged in a line. Also, the proportions of individual bones are typical for most Passeriformes: (15) the coracoid, tarsometatarsus and tibiotarsus are long and slender, the latter being the longest skeletal element; (16) the ulna is longer than the humerus; and (17) the pelvis is of a trapezoidal shape. None of these features is exclusive to Passeriformes, but only representatives of this group of birds show a combination of all these features. Features related to distal wing elements (# 8–11) generally exclude Oscines but are typical of Suboscines.

Differential diagnosis: The specimen differs from: All extant Oscines in: carpometacarpus with narrow distal end of os metacarpale minus that protrudes slightly more distally than os metacarpale majus; phalanx proximalis digiti majoris short, broad and cleaver-shaped, and with a distally directed protrusion in the posterior part of its distal edge; phalanx distalis digiti majoris only slight shorter than phalanx proximalis.
The early Oligocene Wieslochia weissi in: beak length roughly equal to the length of the braincase (in Wieslochia it is clearly shorter); humerus with dorso-ventrally broad proximal epiphysis (in Wieslochia relatively narrower); the brachial index (humerus length/ulna length) larger (0.84 vs 0.74 in Wieslochia).
The early Oligocene specimen NT-LBR-014 from Luberon, France in: the smaller size of all skeletal elements, especially ulna and carpometacarpus, which are more than twenty percent smaller; mandibula with no obvious gonys; coracoid with processus acrocoracoideus directed obliquely upwards (directed more medially in NT-LBR-014); humerus with a well-developed crista deltopectoralis (crista reduced in NT-LBR-014); the brachial index (humerus length/ulna length) larger (0.84 vs 0.77 in NT-LBR-014).
The early Oligocene Jamna szybiaki in: sturdy beak; sternum with elongated and bifurcated spina externa, and processus craniolateralis protruding further anterior than labrum dorsale; carpometacarpus with distal end of os metacarpale minus narrow and protruding only slightly further distally than os metacarpale majus; phalanx proximalis digiti majoris relatively short, broad and cleavershaped, and bearing a distally directed protrusion in its posterior part; phalanx distalis digiti majoris only slightly shorter that the phalanx proximalis.
The early Oligocene Resoviaornis jamrozi in: sturdy beak; thoracic vertebrae not fused to a notarium; carpometacarpus with distal end of os metacarpale minus narrow and protruding only slightly further distally than os metacarpale majus; phalanx proximalis digiti majoris relatively short, broad and cleaver-shaped, and bearing a distally directed protrusion in its posterior part; phalanx distalis digiti majoris only slightly shorter that the phalanx proximalis.
The early Oligocene Winnicavis gorskii in: the brachial index (humerus length/ulna length) larger (0.84 vs 0.79 in Winnicavis); phalanx distalis digiti majoris only slightly shorter than the phalanx proximalis (phalanx noticeably shorter in Winnicavis).
The extinct passerine-like family Zygodactylidae in: sternum with elongated and bifurcated spina externa, and only one pair of incisions in the caudal margin; coracoid with small and rounded processus lateralis; ulna with prominent olecranon that projects far proximally and tapers; phalanx digiti alulae without ungual phalanx; foot with anisodactyl arrangement of toes, with three digits directed forward and the hallux directed backward.

Crosnoornis nargizia gen. et sp. nov.

Etymology: The species is named after Nargiz Salwa, the wife of the finder and co-author of this paper, Grzegorz Salwa.

Holotype: MSFK RR 01/2013a + b (Figs. 1, 2, S1–S7), complete articulated skeleton preserved on two slabs, deposited at the Institute of Systematics and Evolution of Animals, PAS, Kraków, Poland.

Type locality and horizon: Rudawka Rymanowska, exposure 01 (i.e., RU 01 sensu Bieńkowska 2004), the Wisłok River valley, ca. 20 km south-east of Krosno, Podkarpackie Voivodeship, SE Poland. Rupelian, Oligocene, ca. 32–30 MYA, Tylawa Limestones horizon, correlated with the calcareous nannoplankton of the NP 23 zone (Bieńkowska-Wasiluk 2010).

Diagnosis: As for the genus.

Fred


Fig. 1 Crosnoornis nargizia gen. et sp. nov., holotype, specimen MSFK RR 01/2013a + b from Rudawka Rymanowska, exposure 01, Poland, early Oligocene (left) and interpretative drawings (right) with only the main skeletal elements indicated. a slab A; b slab B. Left (L) and right (R) elements are indicated. Abbreviations: cmc carpometacarpus cor coracoid, d1-d4 digit 1–4, fem femur, hum humerus, pal phalanx digiti alulae, pdm phalanx distalis digiti majoris, pmi phalanx digiti minoris, ppm phalanx proximalis digiti majoris, qu quadratum, rad radius, scap scapula, tbt tibiotarsus, tmt tarsometatarsus, tr tracheal rings, vr vertebrae.
 

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