Patriofelis

Early history Some time in 1869, geologist Ferdinand Vandeveer Hayden recovered a pair of partial mandibular rami (the structures which comprise each side of the lower jaw) from strata belonging to the Bridger Formation. These bones were later catalogued as USNM V105. In a March 1870 publication in the Proceedings of the Philadelphia Academy, palaeontologist Joseph Leidy described the jaw scientifically, making it the holotype of a new genus and species, Patriofelis ulta. He believed that P. ulta was an early member of Felidae, the cat family, hence its name. Two years later, in August 1872, Othniel Charles Marsh described the remains of a "gigantic Carnivore" from the same locality, to which he assigned the name Limnofelis ferox. Marsh's specimen consisted of skull material (including a lower jaw), vertebrae, and "other less important parts of the skeleton". Marsh also described a second species, L. latidens, from an upper premolar from the same locality. In 1892, Wortman suggested a second Protopsalis, P. leidyanus, based on remains in the Princeton Collection. Two years later, Wortman published a paper discussing the osteology of Patriofelis ulta. He determined that the other taxa could be rendered junior synonyms, as there was no convincing evidence in the form of diagnostic traits that they were different taxa. Classification Patriofelis is a member of the family Oxyaenidae, which is in turn part of the order Oxyaenodonta. Oxyaenids were at one point considered members of a larger order, Creodonta, alongside hyaenodonts. More recent papers have not supported the monophyly of creodonts, == Description ==

Size Patriofelis is the largest oxyaenid from which postcranial remains are known. Wortman suggested that its overall body size was roughly equal to that of a black bear, though was working under the assumption of felid affinities. In a 2010 publication, Michael Morlo, Gregg F. Gunnell, and Doris Nagel provided general body mass estimates for both Patriofelis species of . In a 2024 paper, Mark S. Juhn and colleagues used a scaling method proposed by Van Valkenburgh in 1990, wherein the size of the largest lower molar was used in a regression analysis, to calculate the body sizes of various extinct mammalian predators, listing their mass estimates in their supplemental materials. Using this method they obtained a body mass of for P. ulta, and a larger body mass of for the larger P. ferox. or to those of hyaenids. True bone-crushing is unlikely, at least in Patriofelis, as P. ulta's dentition overall lacks adaptations for durophagy. The limbs of Patriofelis, particularly its forelimbs, were fairly short and robust. The deltopectoral crest of the humerus (the long bone of the upper forelimb) was "immensely developed", extending two-thirds down the length of the humeral shaft. Regressions found the humeri of Patriofelis to have been more robust than any felid. In the case of P. ferox, the scar on the deltoid of the deltopectoral crest was located more distally than a felid of comparable size. The bones of the forearm were extremely robust, especially the ulna. The ulna had a very robust, medially angled olecranon; it and the semilunar notch account for about a third of the bone's total length, longer than that of carnivorans. Though some have interpreted the morphology of the radius as a sign that Patriofelis was capable only of limited arm rotation, it is likely that it was capable of a strong degree of both pronation and supination. The metacarpals (the bones of the forefeet) were short and robust, arranged and angled in such a way that the feet would likely have been splayed in life, and the same is true of the hind feet. Each digit was tipped in thick, blunt claws. The ilium of Patriofelis was fairly small compared to the ischium and pubis, and was trihedral in cross-section due to the presence of a pronounced ridge running along its lateral surface. The acetabulum was fairly shallow. The trochanteric fossa of the femur (the long bone of the upper hindlimb) was deep, extending quite far down the posterior part of the bone. The distal portion of the femur is not known, so the full extent of the fossa is not certain, though it exceeds what is seen in carnivorans. The tibia is slender in comparison to the femur, though is still fairly robust. It bore a prominent cnemial crest, larger than that of Oxyaena. The proximal end of the fibula is characterised by a very robust interosseous crest (one between the tibia and fibula). The patellas (kneecaps) of Patriofelis were similar to those of carnivorans, being generally teardrop-shaped. The calcaneum was fairly robust and generally resembled that of carnivorans with a plantigrade gait, one where the entire foot, including the heel, was pressed flat on the ground while walking. The metatarsals were relatively short and were quite homogenous in length, although the first was shorter than the others and the third was longer. == Palaeobiology ==

-like depiction of Patriofelis ferox by Charles R. Knight, from 1896 J. L. Wortman initially suggested that Patriofelis was a semi-aquatic, otter-like predator, one which might have specialised in hunting turtles. In their 2022 reassessment of Patriofelis' postcranial anatomy, Anne E. Kort and colleagues also re-examined its palaeobiology. Wortman's initial hypothesis that it might have specialised in hunting turtles was discounted, partly due to energetic demands, and partly because Patriofelis did not have the dentition necessary for a durophagous lifestyle. Similarly, they noted that its spinal column bore interlocking structures known as revolute zygapophyses, which would have considerably reduced spinal mobility, thus heavily restricting the sagittal (up-and-down) motion many mammals use to swim. Furthermore, such inflexibility would have reduced its climbing ability, as arboreal habits require a wide range of motion throughout the dorsal vertebrae. It also lacked the long phalanges (digit bones) and curved claws demanded by such a lifestyle. Korte and colleagues concluded that Patriofelis was probably a terrestrial ambush hunter, one adapted for grappling prey with its strong forelimbs. == Palaeoecology ==

Patriofelis lived in North America during the Bridgerian North American Land Mammal Age, or NALMA (part of the early-middle Eocene, 50.3–46.2 Ma). Fossils of both species have been found in formations in Wyoming (Bridger), and Oregon (Clarno). is the most biodiverse assemblage of fossil flora yet recorded, preserving 66 genera and 76 species of trees and around 173 species of plants overall. Some of the Nut Beds flora is known exclusively from wood, though other plants are known from additional material. Overall there is great floral overlap between the Nut Beds and modern environments, with hamamelidaceans (witch-hazels), rosaceans (roses and their relatives), and pinaceans (pine trees) being known, among others. The reconstructed palaeoenvironment of the Clarno Formation indicates that Patriofelis would have inhabited wet, semitropical forested ecosystems, of the sort which covered much of North America during the early-middle Eocene. of the Bridger Formation, which preserves an environment which alternated between marshlands with braided streams and vast yet shallow lakes. It also preserves the same kind of semitropical forest as the Clarno Formation. Both species of Patriofelis are recorded in the Bridger Formation, although only P. ulta is known from the lower portion. Also known from the Black Forks Member are catfish, salamanders, frogs, varanid lizards, boas, turtles, several crocodilians, the primates Anaptomorphus, Notharctus, Omomys, Trogolemur, Smilodectes, and Uintasorex, the tillodonts Trogosus and Tillodon, the pholidotans (pangolin relatives) Metacheiromys and Tetrapassalus mckennai, various rodents in the families Cylindrodontidae, Paramyidae, and Sciuravidae, the mesonychids Harpagolestes and Mesonyx, the hyaenodonts Limnocyon, Sinopa, Thinocyon, and Tritemnodon, the oxyaenodont Machaeroides, the carnivorans Miacis, Oodectes, Palaearctonyx, Uintacyon, Viverravus, and Vulpavus, the hyopsodont Hyopsodus, the dinoceratan Bathyopsis, the equid Orohippus, the brontotheres Limnohyops and Palaeosyops, the helaletid Helaletes, the hyrachyid Hyrachyus, the dichobunids Antiacodon and Microsus, and the helohyid Helohyus. In a 2019 thesis, Anne E. Kort noted that Patriofelis would have been among the top predators, alongside crocodilians and perhaps the mesonychids, of the environments it inhabited. However, compared to Patriofelis, mesonychids had dentition more adapted for scavenging, were more cursorial, and had a broader distribution. Extinction In her 2019 thesis, Anne K. Kort suggested that the extinction of the genus, and perhaps of oxyaenids as a whole the inability to adapt to changing environments. During the second half of the Eocene, dense, swampy, subtropical forests transitioned to more temperate, open forests. The short, flexible limbs, and plantigrade feet would've been advantageous in navigating through swampy, dense forests, but detrimental in large open environments. In addition, the inflexible spine of Patriofelis further prevented long distance mobility due to the restricted sagittal movements of the spine in locomotion. Patriofelis was successful in densely, swampy forested environments, however it lost that ability as forests became less dense and in addition to their prey, perissodactyls and artiodactyls, already adapted cursorial features prior to the environmental shifts. == Notes ==