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Thegornis sosae sp. nov. (1 Viewer)

Fred Ruhe

Well-known member
Federico L. Agnolín (2023)

A new species of the Falcon genus Thegornis (Aves) from the Miocene of Northwestern Argentina.

Historia Natural (tercera serie) 13 (2): 15-24.

Free pdf: https://fundacionazara.org.ar/img/revista-historia-natural/tercera-serie-volumen-13-2-2023/HN_13_2_15-24.pdf


The aim of the present contribution is to describe a new species of the extinct falcon genus Thegornis. The species is based on the distal end of a tarsometatarsus coming from late Miocene beds of Catamarca province, Argentina. The new taxon is distinguished from closely related forms by details in tarsometatarsus trochleae. It constitutes the second bird genus from Miocene Catamarca province that is shared with fossil bird assemblages of early-middle Miocene of Santa Cruz province, Argentina.


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Falconiformes Sharpe, 1874
Falconidae Leach, 1820
Herpetotherinae Lesson, 1842
Genus Thegornis Ameghino, 1895

Thegornis sosae nov. sp.

Holotype. MACN PV 5431, distal end of left tarsometatarsus

Diagnosis. Large species of the genus Thegornis, the size of T. musculosus, which
difers from other species of the genus by the following combination of characters
trochlea III with its lateral surface strongly concave, which results in a more obliquely oriented trochlear body (straight to slightly convex lateral margin in S. spivacowi and S. musculosus), trochlea III closely appressed to trochlea IV (widely spaced by a wide intertrochlear incisure in T. spivacowi and T. musculosus), and trochlea IV subquadrangular in contour (subrectangular in contour in T. spivacowi and T. musculosus, being proximodistally longer than transversely wide), proximodistally narrow posteromedial wing of trochlea II, which results in a subtriangular contour in side view (similar to T. musculsus, but much stouter and subtriangular in contour in side view in T. spivacowi).

Etymology. The species is named in honor of the singer and performer Haydeé Mercedes Sosa (1935-2009) who represented the northwestern Argentinean roots in the folk music.

Dtratgraphy: Late Miocene beds of Catamarca province, northwestern Argentina., an unknown exact locality of the Puerta de Corral Quemado area, at Santa María Department, Catamarca province, Argentina. There is no indication of collector or date of collection of the material.


Figure 1 - Thegornis sosae nov. sp. (MACN PV 5431, holotype), distal end of left tarsometatarsus in A, anterior; B, medial; C, posterior; and D, lateral views. Abbreviations. asII, anterior articular surface of trochlea II; asIII, anterior articular surface of trochlea III; adII, impression of the m. adductor digiti II; eg, extensor groove of digit IV; iI, metatarsal I fossa; plw, posterolateral wing; pmw, posteromedial wing; lr, lateral ridge; vf, distal vascular foramen. II-IV, metatarsal trochleae. Scale bar. 1 cm.
Remarks by me: tre new species is compared with Thegornis spivacowi and Thegornis musculosus but unmfortunately the species Thegornis spivacowi is umknown by me. I'l try to fond out molre about Thegornis spivacowi
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S. spivacowi and S. musculosus) read T. spivacowi and T. musculosus)

Dtratgraphy: read: Stratigraphy


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