Kaririavis mater gen, et sp. nov. (1 Viewer)

[Fred Ruhe]

Ismar de Souza Carvalho, Federico L. Agnolin, Sebastián Rozadilla, Fernando E. Novas, José A. Ferreira Gomes Andrade & José Xavier-Neto, 2021

A new ornithuromorph bird from the Lower Cretaceous of South America

Journal of Vertebrate Paleontology. Online edition: e1988623. doi:10.1080/02724634.2021.1988623

Abstract: https://www.tandfonline.com/doi/abs/10.1080/02724634.2021.1988623?journalCode=ujvp20

The fossil record of Early Cretaceous birds in South America has been restricted to members of Enantiornithes from the Crato Formation (Aptian) of Brazil. Here we describe a new genus and species of bird discovered at Pedra Branca Mine, Nova Olinda County, Ceará State, Brazil, which adds to the avian fossil record from the Crato Formation. The specimen is represented by an isolated foot that is exposed in plantar view. A plantarly displaced metatarsal III with a well-developed hypotarsus supports its referral to Ornithuromorpha, representing the oldest member of the clade reported for Gondwana. Its unique foot conformation indicates that it may belong to an unknown ornithuromorph clade with some cursory similarities to extant flightless ratites. The presence of Early Cretaceous ornithuromorphs in Brazil indicates that the clade was widespread in Gondwana during the Mesozoic.

http://zoobank.org/urn:lsid:zoobank.org:pub:08333BA3-F231-4E61-9E89-105C7478AE31

The species described is: Kaririavis mater gen. et sp. nov.

Enjoy,

Fred

 

[Fred Ruhe]

SYSTEMATIC PALEONTOLOGY

AVIALAE Gauthier, 1986
ORNITHOTHORACES Chiappe and Calvo, 1994
ORNITHUROMORPHA Chiappe, 2002
KARIRIAVIS MATER, gen. et sp. nov.

Holotype––Macrofossils Collection of Universidade Federal do Rio de Janeiro, Department of Geology (UFRJ-DG), code number UFRJ-DG 116 Av. Slab and counterslab including partial right pes, a nearly complete tarsometatarsus and several apparently unconnected pedal phalanges, which are tentatively identified as follows: digit II phalanges 1 and 2; digit III phalanges 1 to 3; two indeterminate phalanges of digit IV; ungual phalanx of digit II (Figs. 2–4). At least 10 contour feathers are preserved in close association with the foot bones.

Etymology–The genus name is coined from Kariri, in reference to the Karirí people of northeastern Brazil, and avis, from the Latin ‘bird’; gender is feminine. The species epithet is derived from the Latin mater: ‘mother’, for being the oldest ornithuromorph from South America.

Locality and Horizon––The specimen reported herein comes from Pedra Branca Mine, Nova Olinda County, Ceará State, Brazil (7°7’25"S, 39°42’7"W; Fig. 1). The specimen was found in strata belonging to the Crato Formation, Lower Cretaceous (Aptian; Carvalho et al., 2019).

Diagnosis–Kaririavis mater, gen. et sp. nov. is a sparrow-sized bird displaying the following features that are characteristic for Ornithuromorpha: a plantarly displaced metatarsal III, and a well-developed hypotarsus. Kaririavis mater differs from Ornithurae in having metatarsal fusion restricted to proximal end, very shallow proximal intercotylar eminence, and distally open vascular foramen between metatarsals III and IV. Kaririavis mater is diagnosable on the basis of the following combination of characters (autapomorphies marked with an asterisk*) that distinguishes it from other Cretaceous members of Ornithuromorpha: proximal end of metatarsal II not expanded and overlapped plantarly by metatarsal III, shaft of metatarsal II thinner than metatarsal IV, hypotarsus distally extended and forming a mediolaterally thick crest that extends distally beyond the mid-length of metatarsal III*, distal metatarsal III with a small lateral flange defining a vascular opening with metatarsal IV, trochlea of metatarsal III with prominent lateral condyle, and proportionally large ungual phalanx of digit II, representing 1/3 of the total length of the tarsometatarsus.

Measurements––Maximum proximodistal length of metatarsal II: 17.5 mm; maximum proximodistal length of metatarsal III: 19.6 mm; maximum proximodistal length of metatarsal IV: 18.3 mm; maximum proximodistal length of ungual phalanx: 6.6 mm.

Fred


FIGURE 1. A, slab of the holotype of Kaririavis mater, gen. et sp. nov. (UFRJ-DG 116 Av) from the Lower Cretaceous Crato Formation in Brazil, right side in dorsal view. B, interpretative drawing. Broken areas shaded in gray. Abbreviations: cap, metatarsal cap; co, distal condyle of phalanx; lc, lateral condyle; mt, metatarsal; ph, phalanx; un, ungual phalanx of digit II; vg, ventral groove. Scale bar equals 5 mm.

FIGURE 2. A, counterslab of the holotype of Kaririavis mater, gen. et sp. nov. (UFRJ-DG 116 Av) from the Lower Cretaceous Crato Formation in Brazil, right side in plantar view. B, interpretative drawing. Broken areas haded in gray. Abbreviations: cap, metatarsal cap; cg, collateral groove; cr, plantar crest; fl, flange; fr, feather rachis; ft, flexor tubercle; gr, longitudinal groove of hypotarsus; lc, lateral condyle; mc, medial condyle; mt, metatarsal; ph, phalanx; un, ungual phalanx of digit II; vf, vascular foramen Scale bar equals 5 mm.

FIGURE 3. Strict consensus tree showing the phylogenetic position of Kaririavis mater, gen. et sp. nov. (UFRJ-DG 116 Av) among avialans. Data matrix taken from Wang, O’Connor et al. (2020; see Supplemental Data). Abbreviations: Confuciu., Confuciusornithidae; Jinguo., Jinguofortisidae; ORNIT., Ornithuromorpha.