| Patriofelis | |
|---|---|
 | |
| Patriofelis ferox skeleton in storage at theAmerican Museum of Natural History | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | †Oxyaenodonta |
| Family: | †Oxyaenidae |
| Subfamily: | †Oxyaeninae |
| Genus: | †Patriofelis Leidy, 1872 |
| Type species | |
| †Patriofelis ulta Leidy, 1870 | |
| Species | |
| Synonyms[3] | |
synonyms of genus:
synonyms of species:
| |
Patriofelis ("father of cats") is anextinctgenus of carnivorous placental mammals from the extinct subfamilyOxyaeninae within the extinct familyOxyaenidae, which lived from the early to middleEocene. The first remains were discovered in 1869 by geologistFerdinand Vandeveer Hayden, and the genus was named the following year byJoseph Leidy. Over the next few decades, additional specimens would be named from the same locality (or similar ones), many assigned to genera of their own or to separate species withinPatriofelis. Now, only two are recognised:Patriofelis ulta, the type species, from the lowerBridger Formation and theHuerfano Formation of Colorado, andP. ferox, from the lower Bridger and lowerWashakie Formations of Wyoming and Colorado, and theClarno Formations at the John Day Fossil Beds National Monument, Oregon.
Patriofelis is the largest oxyaenid to preservepostcranial fossils (fossils which come from behind the skull).P. ulta, the smaller species, has been estimated at around 30.66 kg (67.6 lb), while the largerP. ferox has been estimated at 55.06 kg (121.4 lb).Patriofelis had a skull around the same size as of that of alion, though shorter and broader in a way often likened tootters. A semi-aquatic lifestyle has been suggested forPatriofelis, though there are aspects of its anatomy which make this very unlikely. Itsbackbone was stiffened by bony structures which projected from itsvertebrae, inhibiting the usual mammalian swimming method, in which the spine undulates up and down. Originally it was suggested to be aturtle specialist, though its teeth were not adapted for crushing, but rather for slicing. While some older sources reported thatPatriofelis had limited arm flexibility, recent studies have shown that its forearms were capable of a great degree ofpronation andsupination. Though there are various hypotheses for howPatriofelis lived, the most likely is that it was a terrestrialambush predator which hunted by grappling its prey.
Patriofelis was among the top predators of at least some localities, competing with certaincrocodilians and withmesonychids. During the early to middle Eocene, much of North America was covered in wetsubtropical forest andmarshland, andPatriofelis was present in geologic formations corresponding to both of these environments. It has been suggested that the extinction of the genus, along with other oxyaenids, corresponded with a shift in available habitat, as the end of the Eocene was marked by a period of cooling and drying which led to the replacement of dense, swampy, forests to more temperate open forests.
Some time in 1869, geologistFerdinand Vandeveer Hayden recovered a pair of partialmandibular rami (the structures which comprise each side of the lower jaw) from strata belonging to theBridger Formation. These bones were later catalogued as USNM V105.[8] In a March 1870 publication in the Proceedings of the Philadelphia Academy, palaeontologistJoseph Leidy described the jaw scientifically, making it theholotype of a new genus and species,Patriofelis ulta. He believed thatP. ulta was an early member of Felidae, the cat family, hence its name.[9][10][11] Two years later, in August 1872,Othniel Charles Marsh described the remains of a "giganticCarnivore" from the same locality, to which he assigned the nameLimnofelis ferox. Marsh's specimen consisted of skull material (including a lower jaw),vertebrae,[12] and "other less important parts of the skeleton".[13] Marsh also described a second species,L. latidens, from an upperpremolar from the same locality.[12]
In the summer of 1879, Jacob Lawson Wortman discovered teeth and limb bones from another specimen.[13] These remains came to the attention of Edward Drinker Cope, who, in 1880, gave them thebinomial name ofProtopsalis tigrinus.[14] In 1892, Wortman suggested a secondProtopsalis,P. leidyanus, based on remains in thePrinceton Collection. Two years later, Wortman published a paper discussing the osteology ofPatriofelis ulta. He determined that the other taxa could be renderedjunior synonyms, as there was no convincing evidence in the form of diagnostic traits that they were different taxa.[13] Several other species have been described which have been consistently synonymised, leaving onlyP. ferox andP. ulta as valid species.[3][15]
Two relatively complete specimens ofPatriofelis (UMNH VP 550 and CM 87673) have been discovered in the interim, both in 1953.[15] The first of these served as the foundation of a 1957 paper onP. ulta's skull anatomy byCharles Lewis Gazin.[11] Both were redescribed by Anne E. Kort and colleagues in 2022, and served as the basis of a description ofPatriofelis' postcranial anatomy.[15]
Patriofelis is a member of the familyOxyaenidae, which is in turn part of the orderOxyaenodonta. Oxyaenids were at one point considered members of a larger order,Creodonta, alongsidehyaenodonts. More recent papers have not supported the monophyly of creodonts,[16][15] and the link between the two is predicated largely on the presence of a blade on themetastyle of the firstmolar, a trait present in manyeutherians.[17]
Patriofelis is the largest oxyaenid from which postcranial remains are known.[18] 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.[13] Thetype species, ofPatriofelis,P.ulta, was the smaller species, weighing at least 30 kg (66 lb).[15][19] In a 2010 publication, Michael Morlo, Gregg F. Gunnell, and Doris Nagel provided general body mass estimates for bothPatriofelis species of 30–100 kg (66–220 lb)[20]. 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 lowermolar was used in aregression analysis,[21] 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 30.66 kg (67.6 lb) forP. ulta, and a larger body mass of 55.06 kg (121.4 lb) for the largerP. ferox.[19]
The skull ofPatriofelis ulta described by Wortman was roughly the same size as that of alion. He noted that it was fairly short, broad and low, and he likened it to the skulls ofseals,[13] though his initial restoration was inaccurate in that it depicted the skull as higher than it actually would have been.Charles Lewis Gazin noted that not only was the modification of its skull more extreme than how Wortman had depicted it, but it was superficially akin to that of anotter. Thepremaxilla inP. ulta was fairly reduced, forming a narrow rim of bone along theanterior (front) margin of themaxilla. The maxillae were fairly short when viewed from the side, although their nasal processes were very long, extendingposteriorly (rearward) over thelacrimal bones. Thenasals ofP. ulta were broad anteriorly, tapering posteriorly and widening yet again around thesutures between the maxillae andfrontals, after which they once again tapered. The frontals were broad anteriorly and tapered posteriorly. Theparietals were long and slender, supporting a fairly well-developedsagittal crest.P. ulta's orbits (eye sockets) were not particularly large, though were positioned dorsally (high up) on the skull.[11] Thezygomatic arches, formed from the jugals andsquamosals, were broad and massively built.[11] Themastoid regions of thetemporal bones were very large and prominent, and theparoccipitals were conspicuous.P. ulta'sbraincase was overall very small, with very thick walls. As with the rest of the skull,P. ulta's mandible (lower jaw) was heavy and robust, with shortmandibular rami andmandibular symphyses. It is fairly rounded anteriorly. Thecondyles of themasseteric fossa were fairly low, extending quite far transversely (across) and being structured similarly to those of cats. The fossa was fairly rounded in angle, similar to that ofOxyaena.[13]
The brain anatomy ofP. ulta is known in part from anendocast. Itscerebellum was fairly large, with a thickly walled cavity, and was not at all covered by thecerebral lobes. As in many Palaeogene mammalian carnivores, the cerebral cavity had at least two longitudinalconvolutions. It is not certain if acrucial sulcus was present.[13]
Thedental formula ofPatriofelis is uncertain, though was rendered by Gazin as2.1.3.1–22–3.1.3.2 × 2 = 32–34.[a] Its teeth were very robust in comparison to other oxyaenid teeth, and have been variously compared to those offelids,[22] or to those ofhyaenids.[11] The upperincisors were fairly simple, with the medial (inner) pair being smaller than the lateral (outer) pair. The lateral pair were far larger and were somewhat caniniform. The true uppercanines were very robust, with deep roots. They were oval-shaped in cross section, as opposed to being sabrelike or laterally compressed, and in the specimen studied by Gazin they had been blunted by wear. In 1900,Henry Fairfield Osborn noted that oxyaenidcheek teeth bore adaptations for slicing and for cutting into bone, such as the loss of thetalonid, as in felids.[23] True bone-crushing is unlikely, at least inPatriofelis, asP. ulta's dentition overall lacks adaptations fordurophagy.[15]P. ulta lacked a first upperpremolar. The second was simple, with two roots and a broad posterior region. The third had three roots with a small anteriorcuspule. The fourth had a higher anteriorcusp, and a projection (also found in the preceding teeth, albeit smaller) which was equal in size to the main cusp but more bladelike in morphology. The first upper molar formed acarnassial, a specialised shearing blade, while the second, if present, was small and peglike, and difficult to make out due to its angle. The number of lower incisors apparently varied between specimens, though the one studied by Gazin had two. As with the upper jaw, the lateral lower incisor was the larger one, though was less procumbent. Both sets were somewhat blunted due to wear. The canines were robust, massively rooted, and close together, and were similarly worn. The second lower premolar ofP. ulta was separated from the canine by a shortdiastema (gap), whereas that ofP. ferox was oblique to it. It was double-rooted and broad. The third was similar but far larger and more robust. The fourth was larger still, with higher cusps and a more pronounced crest on its lingual (inner) margin. It was tilted backwards somewhat. The first lower molar was small, with ametaconid which extended upward and posterolingually (inward and rearward) from theprotoconid. Similar to the first upper molar, the second lower molar formed a shearing surface and lacked atalonid.[11]
_(20240722478).jpg)
Patriofelis had sevencervical (neck)vertebrae, of which five are known from UMNH VP 550. In both species, all of the vertebrae beyond the axis had robusttransverse processes. The sixth cervical vertebra is long and angled more ventrally than in modern carnivorans. Noneural spines are known fromP. ulta, although those ofP. ferox were decently large, and it is likely the same is true of both species.[15] Beyond the neck,Patriofelis' spinal column bore a series of interlocking projections called revolutezygapophyses, which would have restricted the mobility of the spine.[15] Thethoracic (upper back) vertebrae, of which there were thirteen,[13] were smaller than thelumbar (lower back) vertebrae, with proportionally larger vertebral centra.[15] There were six lumbar vertebrae, which bore flat-fronted centra with strong inferior (lower) keels, giving them a shape like atrihedron. There were threesacral vertebrae. The sacrum overall was robust to in order to support both the vertebrae in front of it and a large, powerful tail. There were twenty-eightcaudal (tail) vertebrae, with the anterior ones being larger and more robust than those further back.[13] The tail overall was unusually long and thick in comparison to that of many former creodonts.[24]
The limbs ofPatriofelis, particularly its forelimbs, were fairly short and robust. Thedeltopectoral crest of thehumerus (thelong bone of the upper forelimb) was "immensely developed", extending two-thirds down the length of the humeral shaft.[24] Regressions found the humeri ofPatriofelis to have been more robust than anyfelid. In the case ofP. ferox, the scar on the deltoid of the deltopectoral crest was located more distally than a felid of comparable size.[18] The bones of the forearm were extremely robust, especially theulna.[24] The ulna had a very robust, medially angledolecranon; it and thesemilunar notch account for about a third of the bone's total length, longer than that of carnivorans.[15] Though some have interpreted the morphology of theradius as a sign thatPatriofelis was capable only of limited arm rotation,[24] it is likely that it was capable of a strong degree of bothpronation andsupination. Themetacarpals (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.[15][24] Theilium ofPatriofelis was fairly small compared to theischium andpubis, and was trihedral in cross-section due to the presence of a pronounced ridge running along its lateral surface. Theacetabulum was fairly shallow. The trochantericfossa of thefemur (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. Thetibia is slender in comparison to the femur, though is still fairly robust. It bore a prominentcnemial crest, larger than that ofOxyaena. The proximal end of thefibula is characterised by a very robust interosseous crest (one between the tibia and fibula). The patellas (kneecaps) ofPatriofelis were similar to those of carnivorans, being generally teardrop-shaped. Thecalcaneum was fairly robust and generally resembled that of carnivorans with aplantigrade gait, one where the entire foot, including the heel, was pressed flat on the ground while walking. Themetatarsals were relatively short and were quite homogenous in length, although the first was shorter than the others and the third was longer.[15]
J. L. Wortman initially suggested thatPatriofelis was a semi-aquatic,otter-like predator, one which might have specialised in huntingturtles.[13] Henry Fairfield Osborn disagreed with this assessment, arguing in 1900 that it was an arboreal predator which behaved similarly to cats.[23]William Diller Matthew in 1909 disagreed with both ideas, as its short limbs and blunt claws would have made it more suited for hunting on the ground.[25] In their 2022 reassessment ofPatriofelis' 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 becausePatriofelis 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 thedorsal vertebrae. It also lacked the longphalanges (digit bones) and curved claws demanded by such a lifestyle. Korte and colleagues concluded thatPatriofelis was probably a terrestrial ambush hunter, one adapted for grappling prey with its strong forelimbs.[15]
Patriofelis lived inNorth America during theBridgerianNorth American Land Mammal Age, or NALMA (part of the early-middleEocene, 50.3–46.2 Ma). Fossils of both species have been found in formations inWyoming (Bridger),[26][27]Colorado (Huerfano andWashakie),[28][29] andOregon (Clarno).[15]
One of the environmentsPatriofelis (and specificallyP. ferox) inhabited, the depositional environment for the so-called Nut Beds of theClarno Formation,[30] 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, withhamamelidaceans (witch-hazels),rosaceans (roses and their relatives), andpinaceans (pine trees) being known, among others.[31] The reconstructed palaeoenvironment of the Clarno Formation indicates thatPatriofelis would have inhabited wet,semitropical forested ecosystems,[31][26] of the sort which covered much of North America during the early-middle Eocene.[26]
Patriofelis is also known from the Black Forks Member, the lower member (consisting of Units A and B)[27] of theBridger 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 ofPatriofelis are recorded in the Bridger Formation, although onlyP. ulta is known from the lower portion. Also known from the Black Forks Member arecatfish,salamanders,frogs,varanid lizards,boas, turtles, severalcrocodilians,[26] the primatesAnaptomorphus,Notharctus,Omomys,Trogolemur,Smilodectes, andUintasorex, the tillodontsTrogosus andTillodon, thepholidotans (pangolin relatives)Metacheiromys andTetrapassalus mckennai, various rodents in the familiesCylindrodontidae,Paramyidae, andSciuravidae, the mesonychidsHarpagolestes andMesonyx, the hyaenodontsLimnocyon,Sinopa,Thinocyon, andTritemnodon, the oxyaenodontMachaeroides, the carnivoransMiacis,Oodectes,Palaearctonyx,Uintacyon,Viverravus, andVulpavus, the hyopsodontHyopsodus, the dinoceratanBathyopsis, the equidOrohippus, the brontotheresLimnohyops andPalaeosyops, the helaletidHelaletes, the hyrachyidHyrachyus, the dichobunidsAntiacodon andMicrosus, and the helohyidHelohyus.[27]
In a 2019 thesis, Anne E. Kort noted thatPatriofelis would have been among the top predators, alongside crocodilians and perhaps the mesonychids, of the environments it inhabited.[26]
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 ofPatriofelis 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 andartiodactyls, already adapted cursorial features prior to the environmental shifts.[26]
