Devincenzia

Holotype (MNHN-M-189) tarsometatarsus of Devincenzia gallinali.

In 1931, a very large distal right tarsometatarsus associated with a ungual phalanx from digit II, was described by the Uruguayan Paleontologist Lucas Kraglievich as a new species of Phororhacos (a misspelling of Phorusrhacos), P. pozzi and deposited at the Museo Argentino de Ciencias Naturales Bernardino Rivadavia in Buenos Aires, Argentina under specimen numbers MACN-6554 and 6681.[2][3] The fossils had been found in Lower Pliocene rock layers at El Brete in Cordoba, Argentina, specifically from the Mesopotamian.[3] The name was after the lead taxidermist at the museum, Antonio Pozzi. Later in the same paper, Kraglievich named a subspecies of Phororhacos (Phorusrhacos) longissimus mendocinus based on a partial proximal right femur from the Late Miocene Huayquerías Formation in Mendoza, Argentina.[4] The subspecies has since been synonymized with Devincenzia pozzi.[2] [5]Kraglievich also referred a synphysis fragment to Phororhacos (Phorusrhacos) platygnathus, but the fossil has since been referred to Devincenzia pozzi.[2][4][3] The next year, Kraglievich named a new genus and species of Phorusrhacid from Argentina based on a partial right tarsometatarsus of a juvenile individual (MNHN-M-189), naming it Devincenzia gallinali. The generic name comes from museum director Garibaldi Devincenzi and the specific name comes from Alejandro Gallinal, another Uruguayan scientist.[6][2] The origin of the fossil is unknown, with Kraglievich initially speculating that it was from Uruguay, but the coloration corroborates with that of Patagonian fossils from the Miocene.[4][2] Although they are sometimes considered distinct,[4] Herculano Alvarenga and Elizabeth Höfling synonymized the two species in 2013 in their reassesment of Phorusrhacidae and moved P. pozzi to Devincenzia in the same paper.[2]

In August of 1936 in a lagoon at Campo de Robilotte on Lake Epecuén, around 600 km southwest of the city of Buenos Aires, Antonio Castro collected a partial skull and two pedal phalanges of a large Phorusrhacid, as well as fossils of other Cenozoic taxa like the armadillo Coscinoceros and ground sloth Elassotherium. The fossils were sent to the Museo de la Plata, where they were described by Angelo Cabrera in 1939, naming the Phorusrhacid specimens (MLP 37-III-7-8) Onactornis depressus. P. pozzi and P. longissimus mendocinus were moved to Onactornis by Pierce Brodkorb, who also believed that Devincenzia gallinali was a synonym of Brontornis.[4] The Ituzaingo Formation also bears Devincenzia fossils, including a pedal phalange, tibiotarsus fragment, tarsometatarsus fragment, a cervical vertebra, and a dorsal vertebra that were referred to D. gallinali based on size and morphology.[2][7] Two other fossil remains include a right tarsometatarsus, about 40 cm long, lacking the inner knuckle, probably from the Arroyo Roman river basin in the Río Negro Department, and the lower articular end of another tarsometatarsus.[7] These specimens come from the upper Pliocene and lower Pleistocene, extending the potential range of the taxon.[7][2]

Devincenzia was one of the largest representatives of Phorusrhacidae. It surpassed the type genus Phorusrhacos, whose total height is given at about 2.4 m, making it potentially the largest phorusrhacid.[2] The probable body weight of Devincenzia is given as about 161 kg.[8] It probably resembled its relatives Phorusrhacos and Kelenken, like them, it was equipped with a narrow body, conspicuously elongated walking legs, and retracted wings.[2] The skull was preserved with the rear part and areas of the upper jaw. Reconstructed, it was probably about 64.5 cm long, which roughly corresponded to the known skull of Phorusrhacos, but was slightly smaller than that of Kelenken. When viewed from above, it had a wedge shape, reaching a width of 32.3 cm at the occipital bone and a height of 12.7 cm. The height of the skull at the back of the head corresponded to about 39% of the width, which is less than in Phorusrhacos with 47% or Psilopterus with 48%. In this regard, the skull of Devincenzia more closely resembled that of Kelenken.[9] It narrowed towards the front, with the width at the frontal bone being 24.4 cm, and at the temporal fossa it drew in significantly and measured 19.1 cm. The frontal bone was very wide, and the two processes occurring there, the processus postorbitalis and the processus supraorbitalis, were separated by a deep recess. The os quadratum appeared comparatively large, differing from that of Psilopterus in addition to the different design of the three extensions, among other things, by the comparatively smaller part of the main bone, which was connected to the cheekbone. Likewise, the os quadratojugale showed a more robust structure and was comparatively higher. Since the upper jaw is incomplete, and only the middle section is available, the dimensions of the beak can only be inferred. Using dimensions from other phorusrhacids, it may have been 36 cm long and 17 cm high. The symphysis of the lower jaw, which has also been handed down in fragments, had a much narrower and lower shape than in Brontornis. It was only preserved to a length of 11 cm, but it would have reached a length of around 16 cm. At the rear end it was 6.2 cm wide and 4.7 cm thick, and towards the front it became significantly lower, measuring about 2.8 cm at half length. The underside had a slight curvature, more pronounced than that of Physornis, which had a nearly flat surface. The externally visible foramina were wide and deep.[10][3]

Of the few surviving elements of the body skeleton, a complete tibiotarsus remained, and it was 72 cm long and 10.4 cm wide at the lower end of the joint, resembling that of Phorusrhacos in its long and slender build, although it was larger. At the lower end of the joint it had a bony bridge (pons supratendineus) that was conspicuous for the phorusrhacids. In addition, the lower inner joint roller protruded further forward than that of Galliformes.[11] An almost complete specimen, missing only the inner jointed roller, reached a length of 40 cm and a width at the top of 11 cm. In the middle of the shaft, the side edges drew in significantly further than in Phorusrhacos, which showed a relatively even course of the diaphysis there. With a width of 4.3 cm, the middle joint roll at the bottom was significantly more voluminous than the other two and indicates that Devincenzia's middle toe was also more massive.[3][2] The first toe of the third (middle) ray measured 12.5 cm in length. It was long and narrow with a width of 5.3 cm and a height of 5.7 cm. The surviving end phalange of the second toe measured around 9 cm, had an oval cross-section, was strongly curved in side view, and was strongly pressed laterally. The width at the joint end facing the body was 2.4 cm and the height was 3.9 cm.[11][2]

Due to the fragmentary and poor descriptions of Devincenzia, its place in Phorusrhacidae is greatly unresolved, though it is most likely a phorusrhacine based on comparisons to Phorusrhacos, Kelenken, and Titanis.[2] The following analysis was conducted in 2020 by Federico J. Degrange.