| Barbourofelis | |
|---|---|
 | |
| B. loveorum, Florida Museum of Natural History Fossil Hall at the University of Florida | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Family: | †Nimravidae |
| Tribe: | †Barbourofelini |
| Genus: | †Barbourofelis Schultz, Schultz & Martin, 1970 |
| Type species | |
| †Barbourofelis fricki Schultz, Schultz & Martin, 1970 | |
| Other Species | |
| |
Barbourofelis is an extinct genus of largefeliform, from the subfamilyBarbourofelinae, which is part of the family of false-sabertooth cats known asNimravidae.Barbourofelis, along withAlbanosmilus, were the last known nimravids.Barbourofelis lived inNorth America andEurasia during theMiocene epoch from 12 to 7Ma.[1][2][3]
Five species are currently recognized within the genus:B. fricki,B. loveorum,B. morrisi,B. oregonensis, andB. piveteaui.B. morrisi likely evolved fromAlbanosmilus migrating into North America. WithB. piveteaui evolving from reverse migration from North America into Eurasia.B. loveorum possibly evolved fromB. morrisi, and may have evolved intoB. fricki.
B. morrisi andB. piveteaui were the smallest species being about as large as aleopard.B. loveorum was the larger thanB. morrisi and may have weighed anywhere from 70–128 kg (154–282 lb).B. fricki was the most recent and largest species of the genus, as well as the largest nimravid. Suggested to have been as large aslions, weighing around 328 kg (723 lb), although a later study suggested it was significantly smaller weighing 256 kg (564 lb).B. oregonensis was described to being similar in size and morphology toB. fricki. It's believed thatBarbourofelis was an ambulatory,ambush predator that hunted within closed forested environments.
Barbourofelis was named byBertrand Schultz, Marian Schultz, and Larry Martin in 1970 in honor ofErwin Hinckley Barbour, who died a few days before theholotype was discovered. Its type species isBarbourofelis fricki and is the type genus of the subfamilyBarbourofelinae.[4] Originally, barbourofelids were considered members of themachairodont subfamily.[5] However, this was called into question, and by the 1980s and 90s barbourofelids were considered to benimravids instead offelids.[6][7][8] In the 2000s, Morlo et al. (2004) argued that barbourofelids ranked as their own family, known asBarbourofelidae.[9] This was also the prevailing view for barbourofelids during the 2010s,[10][11][12] although some experts still considered them to be nimravids.[2]
However, in the 2020s, most experts have reclassified them as nimravids.[13][14][15][3][16][17][18] Most experts classify them as the subfamily Barbourofelinae,[13][14][16][17] although one study proposed them as a tribe, Barbourofelini, within theNimravinae subfamily.[3]
Albanosmilus jourdani is believed to be the ancestor to the genus, which migrated into North America sometime during theLate Miocene.[19]B. morrisi was the earliest species within the genus, probably the result ofAlbanosmilus migrating to North America and was likely ancestral toB. loveorum, which later evolved intoB. fricki.[2] The discovery ofB. piveteau suggestsBarbourofelis reverse migrated back into Eurasia.[20]
._Walking_with_sabertooths_(fig._1).png)
The type species,B. fricki, is considered to have been the largestbarbourofeline, as well as the largestnimravid.[3][21]B. fricki was thought to have been alion-sized predator, having a weight comparable to an African lion, with limb bones indicating a muscular, robust body. Individuals within the species have been reconstructed with shoulder heights of around 90 cm (2 ft 11 in).[21] In 2021, Barret estimated based on m1 length regression,B. fricki may have weighed up to 328 kg (723 lb),[3] however a 2024 study found a much lower body mass of 256 kg (564 lb).[22]Including supplementary materialsB. oregonensis was another large species, described to being similar in size and morphology toB. fricki, although it has some distinctions such as the absence of P4 and M1, as well as a more pronounced transverse.[23]
The smaller species,B. morrisi, was believed to have been closer to the size of a largeleopard and has a shoulder height around 65 cm (2 ft 2 in), being intermediate in size betweenSansanosmilus andB. fricki.[24][21]B. piveteaui is described to being similar in size toB. morrisi.[20]B. loveorum was suggested to have been larger thanB. morrisi.[2] In a 2012 paper, Meachen estimated thatB. loveorum may have weighed 70 kg (150 lb) on average.[25] However, Orcutt and Calde estimated that based on articular width of the humerus, the species may have been larger, weighing between 87–128 kg (192–282 lb), with an average weight of 110 kg (240 lb).[26]
The genus had the longestcanines of all barbourofelines, which were also flattened, indicating a high degree of specialization to its diet. These canines had a longitudinal groove on the lateral surface that has been described as a means of allowing blood from a wound they have inflicted to flow away. This groove more likely was an adaptation to make the canines lighter while maintaining their strength. Other notable traits include the presence of a postorbital bar, the presence of a ventrally extended mental process (bony extensions on either side of the lower jaw), and the shortening of the skull behind the orbits, in addition to having a very robust constitution. The barbourofelin was probably very stocky in build, resembling abear-like lion or lion-like bear. Based on its foot structure, species ofBarbourofelis might have had a semi-plantigrade walking stance.[21]
The most extensive selections of bones found for this genus come fromB. loveorum and have allowed further inference to the proportions of other members of the genus.[21]
A 1988 study found that based on the analysis of the skulls and maxillary materials,Barbourofelis had delayed eruptions of deciduous upper canines, which suggests thatBarbourofelis practiced a long period of parental care.[7] Additionally, skeletons of juvenileBarbourofelis have been found, and examination of their skeletons indicates that the cubs would reach near-adult size before their milk sabers would begin to erupt. This indicates that they were dependent on their mother or potential family group until well into their second year, similar to that of modernlions. Such a long period of dependence would have likely led to situations in which near-adult cubs would have likely helped to restrain prey while their mother made the kill.[21][27]
Barbourofelis was found to have large carnassial teeth, meant it was for efficiently processing a carcass and ate at a fast and competitive manner. This indicated it either lived in a highly competitive ecosystem or that it wassocial, or even a combination of both scenarios.[28] In addition, experts argued due to the delayed eruption of their upper canines may have been further evidence of gregariousness inBarbourofelis.[7][28][27] Although, some authors have suggested thatBarbourofelis was a solitaryambush predator.[29]
Forelimb analysis from a 2021 found thatB. loveorum may have less constrained forelimb movement compared to the contemporarymachairodontNimravides galiani and extantfelids. The increased mobility in the forelimbs suggests it relied on grappling prey and subduing prey, as an ambulatory ambush predator, that walked and trotted around the forest floor similar toursids,wolverines, andbadgers. It would've been opportunistic and attacked prey upon reach, and could've engaged in scavenging similar to wolverines due to their large carnassial teeth. In addition to possibly being able to climb, although it wouldn't have beenarboreal.[30] A 2005 study found that theleopard-sizedB. morrisi had a similar crural index to the lion-sizedSmilodon fatalis, but had a lower brachial index than the machairodont and ambush predators, having an index score closer to that of ambulators. This suggestsB. morrisi had the same leverage asSmilodon. In addition,B. loveroum andB. fricki were found to have even lower brachial and crural indexes thanSmilodon, suggesting that barbourofelins possibly had a greater power output of the limbs thanSmilodon.[31] The robustness of the humerus suggests it could've taken on prey larger than itself.[32]
Previously, it has been suggested by Naples and Martin thatB. fricki had a jaw gape of 115° or greater.[29] However, Lautenschlager et al. (2020) suggests a lower jaw gape forBarbourofelis. Their analysis suggests jaw gapes of 89.13°, 85.29°, and 65.68° forB. fricki,B. loveorum, andB. morrisi respectively.[33]Including supplementary materials
Figueirido et al. (2024) study on the cranial biomechanics ofB. fricki found based on m. masseter pars profunda, this species would've had a maximum jaw gape of 73° and found little evidence to support jaw gapes of over 90°. They also found thatBarbourofelis skull was less stressed when it came to bilateral canine biting compared toSmilodon fatalis. When it came to stabbing, the skull ofBarbourofelis were not as evenly distributed asSmilodon, with regional stresses mainly present in occipital and parietal bones, as well as the upper canines. With pulling-back, stress inSmilodon skull was more evenly distributed thanBarbourofelis, with the stress ofBarbourofelis being concentrated in the premaxilla, parietal-occipital region, postorbital bar, and canines. Despite having a stress resistant skull, the canines were found to be very weak when extrinsic forces are applied due to its sharp and flattened canines, so it would've been able to penetrate more easily thanSmilodon. The authors argued, sinceBarbourofelis skull experiences less stress thanSmilodon, it may have been more generalist in prey killing thanSmilodon.[34]
Despite its derived craniodental adaptations,Barbourofelis brain was similar to that of Oligocenenimravids.[35] Compared to living felids, its brain its anterior lobes were more narrow and the highest point of the cerebrum was situated more caudally.[36]
B. loveorum's environment in theLove Bone Beds deposits (ofClarendonian Age) was a mixture of grassland, riverine forest, and marshes, in which it would have shared territory with herbivorous animals include rhinoceroses such asTeleoceras andAphelops, theprotoceratidSynthetoceras, the camelAepycamelus, horses such asNeohipparion andNannippus, the extinct tapirTapirus webbi, the proboscideanGomphotherium, and carnivores such as the machairodontNimravides galiani, theborophaginae canidEpicyon, and mustelids such asLeptarctus andSthenictis.[37][38][32][39] Forelimb morphology suggestsB. loveorum andN. galiani weren't directly competing with one another, but instead niche partitioned by preferring different habitats. The robust forelimbs ofBarbourofelis suggests it preferred forested environments, whileNimravides preferred more open habitats. This is further supported by forest dwelling fauna such astapirs,Prosthennops,Aepycamelus, andB. loveorum itself being unusually abundant in Love Bone Beds compared to Late Miocene sites. In addition, the shorter metacarpals ofBarbourofelis suggested it hunted smaller prey thanNimravides.[30]
B. fricki roamed western North America being found in states such asKansas,Nebraska,Texas, andNevada from 9 to 7 Ma.[3]Including supplementary materials Within Ambelodon fricki Quarry of Nebraska,B. fricki coexisted with canids such as borophagines canids likeEpicyon hayendi andBorophagus, and an extinct foxVulpes stenognathus, theagriotheriniibearIndarctos oregonensis, the machairodontNimravides, and mustelidSthenictis. Large herbivores present included rhinoceros such asAphelops andTeleoceras, horses such asProtohippus gidleyi,Calippus,Cormohipparion,Dinohippus leidyanus, andNeohipparion trampasense, and the proboscideanAmebelodon fricki.[40]
The extinction ofBarbourofelis, is thought to have been due to faunal overturn in the Late Miocene, not competition with machairodonts.[3][41]