Buteo from the Miocene of Italy (1 Viewer)

[albertonykus]

Pavia, M., S. Cavagna, I. Pellegrino, L. Pellegrino, and G. Carnevale (2022)
The oldest fossil record of Buteo (Aves, Accipitridae) from the Late Miocene of Italy and its evolutionary implications
Bollettino della Società Paleontologica Italiana 61: 145–158
doi: 10.4435/BSPI.2022.11

In this study the presence of Buteo sp. is documented from the Late Miocene (early Messinian MN 13) of Roddi, northwestern Italy. The findings are based on an almost complete skeleton discovered within a 1.5-m-thick succession of laminated grey-brown marls, which have yielded numerous fish and plant remains. Despite the limited osteological information that can be obtained from this fossil, it exhibits some morphological characters that support its attribution to the extant genus Buteo, of which it represents the oldest confirmed record worldwide. It has been suggested that Buteo originated from a Neotropical ancestor, colonized Central and North America after the closure of the Panama Isthmus in the late Cenozoic, and reached Eurasia during the Pleistocene, while the Old World Buteo lineage evolved more recently, during the Late Pleistocene. The specimen from Roddi pushes back the divergence between the Old World and New World Buteo lineages by more than 6 Million years earlier than previously thought. Consequently, a revision of the phylogeny of the Buteoninae, including data from the fossil record, and its paleobiogeographical implications is recommended.

 

[Fred Ruhe]

SYSTEMATIC PALEONTOLOGY

Order Accipitriformes Vieillot, 1816
Family Accipitridae Vigors, 1824
Genus Buteo Lacépède, 1799

Buteo sp.

Material - A nearly complete skeleton (MCCB 03740), in part and counterpart, lacking part of the skull, the distal right wing, and the distal left foot.

Age and locality - Early Messinian at 6.3 Ma (Late Miocene) locality of Roddi, in the vicinity of the city of Alba (Cuneo Province, north-western Italy).

Remarks - Some species of Buteo have been described from the Oligocene and Neogene of North America (Brodkorb, 1964; Cracraft, 1969), although their tentative assignment to Buteo was based on a superficial similarity with the extant species of Buteo, and the authors already recognized that there are some substantial morphological differences (see also Mayr & Perner, 2021). In addition, the synonymisation of Geranoaetus with Buteo proposed by Wetmore (1933) resulted in the attribution of at least nine extinct species from the Oligocene and Neogene of North America (Brodkorb, 1964) to the recent genus Buteo.
The nine species listed by Brodkorb (1964) show similar morphological characters that could be plesiomorphic for most of the Accipitridae, thereby implying that their assignment to Buteo needs re-evaluation (see, e.g., Mayr, 2009, 2022).
Two species of Buteo have also been described from the Miocene of Europe, that is, B. pusillus Ballmann, 1969 and B. spassovi Boev & Kovachev, 1998 from the Middle Miocene of France and the Late Miocene of Bulgaria respectively (Ballmann, 1969; Boev & Kovachev, 1998). The holotypic carpometacarpus of Buteo pusillus shows a number of differences from that of the recent species of Buteo; in particular, the facies articularis ulnocarpalis is concave and not flat, the small crest between the processus pisiformis and the trochlea carpalis is absent, the os metacarpalis alularis is extremely concave in dorsal view, and there is a small tuberculum below the processus pisiformis in ventral view. Although the holotype specimen has been properly described, the characters pointed out by Ballmann (1969) are not apomorphic for the genus Buteo, but more likely synapomorphic for various lineages among the Accipitridae. For those reasons, we consider the attribution of B. pusillus to the genus Buteo as questionable.
Buteo spassovi was described based on a nearly complete tibiotarsus (Boev & Kovachev, 1998). Its generic attribution is only tentative as the original description does not include any apomorphic character of the genus Buteo and the authors solely provided a differential diagnosis with modern and fossil species of Buteo and Milvus. In addition, the illustrations associated with the descriptive analysis are inadequate to understand the actual morphology of the holotypic tibiotarsus. For these reasons, also in the case of B. spassovi, the attribution to the genus Buteo is in need of a revisionary study and will be not considered hereafter. Therefore, based on our current knowledge, the reliable fossil record of the genus Buteo starts from the Pleistocene of the Old World (Mlíkovský, 2002), while its presence in the Oligocene and Neogene of Europe and North America should be necessarily re-examined.

Fred


Fig. 1 - Buteo sp., MCCB 03740, from the Late Miocene of Roddi, part. Cmc: carpometacarpus; rad: radius; uln: ulna; hum: humerus; fem: femur; tibiot: tibiotarsus; tmt: tarsometatarsus; dex: right; sin: left. Scale bar corresponds to 5 cm.

Fig. 2 - Buteo sp., MCCB 03740, from the Late Miocene of Roddi, counterpart. Hum: humerus; cor: coracoid; dex: right; sin: left. Scale bar
corresponds to 5 cm.