Praecarbo strigoniensis gen. nov. et sp. nov. (1 Viewer)

[Fred Ruhe]

Jenő (Eugen) kessler & Ida horváth, 2023

Praecarbo strigoniensis, a new genus and species of Cormorants (Phalacrocoracinae) from the Late Oligocene of Hungary

Ornis Hungarica 2023. 31(1): 126–132

Abstract smd free pdf: a new genus and species of Cormorants (Phalacrocoracinae) from the Late Oligocene of Hungary

The authors describe a fossil avian distal tibiotarsal epiphysis, remains of a cormorant (Phalacrociracinae) differing in age and morphological characters from other fossil cormorants. The fossil material comes from sandy marine deposits from the village of Máriahalom in north-western Hungary, together with the remains of 26 other vertebrate species, mostly marine. The age of the fossiliferous deposit is established in the Late Oligocene, at the beginning of the Chattian stage (MP25–30). The earliest fossil specimens of the subfamily Phalacrocoracinae are known from the Early-Middle Oligocene of North America and Northeast Africa, respectively. The rest of the known specimens are dated to the Late-Upper Oligocene and Lower Miocene. Thus, the fossil described here represents an intermediate age and it is less specialised in morphological characteristics. A new genus and species of cormorants, Praecarbo strigoniensis described here based on the distal epiphysis of a fossil tibiotarsus

Enjoy,

Fred

 

[Fred Ruhe]

Systematic Paleontology

Class Aves Linnaeus, 1758
Order Pelecaniformes (Sharpe, 1891)
Family Phalacrocoracidae (Bonaparte, 1853)
Subfamily Phalacrocoracinae (Bonaparte, 1854)

Genus: Praecarbo n. gen.

Species: Praecarbo strigoniensis n. sp.

Site and age: Máriahalom (Komárom-Esztergom county, Esztergom district, Hungary), Middle-Late Oligocene, (MP25–30), Mányi Formation.

Holotype: right tibiotarsus, distal epiphysis

Name etymology: Praecarbo = genus preceding Phalacrocorax; strigoniensis = from the Latin name of Esztergom (Strigonium).

Genus and species diagnosis: an early ancestor of cormorants with less specialised
subfamily characters. Also lacking the medio-lateral distortion of the distal epiphysis,
indicative of the members of the clade, which also gives the shape of the sulcus extensorius and pons tendineus:
– the sulcus extensorius (a) is wide and extends under the bridge in the middle of the
epiphysis;
– the pons tendineus (b) is almost straight, quite wide, distalolaterally slightly oblique;
– the opening of the canalis extensoius (c) is wide;
– tuberculum retinaculi m. fibularis (d) slightly prominent;
– condylus medialis (e) and condylus lateralis (f) nearly equal in size;
– incisura intercondylaris (g) is wide and deep in distal view.
In comparison with the early cormorant species already mentioned, the sulcus extensorius of the Máriahalom specimen does not extend medially but remains in the middle of the diaphysis until the bridge; the pons tendineus is broader and less oblique than in Oligocorax, Nectornis and Phalacrocorax, and almost identical to Borvocarbo; the canalis extensorius opening is similarly wide as in the other species; the length of the two articular cusps (condylus medialis and lateral) is almost identical, unlike in the other species, where the former is more or less longer; the condylus medialis is not oblique as in Borvocarbo; the incisura intercondylaris is deeper than in Oligocorax and Nectornis.
In size, Praecarbo is slightly smaller than Borvocarbo tardatus, Phalacrocorax carbo, and Nannopterum auritus, and larger than all the other above species. Further, it is probably dated earlier than the other fossil phalacrocoracine species with known tibiotarsus.

Fred

Figure 1. images 1–5. Praecarbo strigoniensis n. gen. et sp. 1. right tibiotarsus, distal epiphysis, cranial aspect; 2. caudal aspect; 3. medial aspect; 4. lateral aspect; 5. distal aspect; g. incisura intercondylaris; images 6–10. extans Phalacrocorax carbo L. 1758; 6. right tibiotarsus, distal epiphysis, cranial aspect; 7. caudal aspect; 8. lateral aspect; 9. medial aspect; 10. distal aspect.

Figure 2. images 1–4. Praecarbo strigoniensis n. gen. et sp. 1. right tibiotarsus, distal epiphysis, cranial aspect, a – sulcus extensorius, b – pons tendineus, c – orifice traverse of canalis extensorius, d – tuberositas musc. fibularis; 2. caudal aspect, e – condylus medialis, f – condylus lateralis, g – incisura intercondylaris; 3. lateral aspect, f – condylus lateralis; 4. medial aspect, e – condylus medialis; images 5–7. measurement method: F – width of distal epiphysis; G1 – thickness of lateral condylus; G2 – thickness of medial condylus