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Pseudaelurus
Temporal range: Miocene
Pseudaelurus jawbone from the Staatliches Museum für Naturkunde Stuttgart, Germany
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Felidae
Genus: †Pseudaelurus
Gervais, 1850
Type species
†Pseudaelurus quadridentatus
(Blainville, 1843) sensu Gervais, 1850
Other Species
  • †P. cuspidatus Wang et al., 1998
  • †P. guangheensis Cao et al., 1990
Synonyms

P. quadridentatus

  • Felis quadridentata Blainville, 1843

Pseudaelurus is a prehistoric cat that lived in Europe, Asia and North America in the Miocene between approximately twenty and eight million years ago. It is considered to be a paraphyletic grade ancestral to living felines and pantherines as well as the extinct machairodonts (saber-tooths), and is a successor to Proailurus. It originated from Eurasia and was the first cat to reach North America, when it entered the continent at about 18.5 Ma ending a 'cat-gap' of 7 million years.[1][2] The slender proportions of the animal, together with its short, viverrid-like legs, suggest that it may have been an agile climber of trees.[3]

Taxonomy and phylogeny

[edit]
Pseudaelurus is located in Earth
Pseudaelurus from Big Beaver A (Ash Hollow), US
Pseudaelurus from Big Spring Canyon, US
Pseudaelurus intrepidus from Forked Hills of Hayden, US
Pseudaelurus from Fort Niobrara (Valentine), US
Pseudaelurus from Immense Journey Quarry, US
Pseudaelurus marshi from Joseph Jamber Quarry, US
Pseudaelurus stouti from Kennesaw (Pawnee Creek Beds), US
Pseudaelurus from Mastodon Quarry, US
Pseudaelurus marshi from Mouth of Minnechaduza Creek, US
Pseudaelurus intrepidus from Trail Creek Quarry (Ash Hollow), US
Pseudaelurus marshi from Valentine Railway Quarries (Valentine), US
Pseudaelurus intrepidus from Valentine Railway Quarries (Valentine), US
Pseudaelurus from Verdigre Quarry (Valentine), US
Pseudaelurus from Wolf Creek (SDSM V-5324), US
Pseudaelurus intrepidus from Rancho El Ocote (Basal) (Rancho Viejo Beds), MX
Pseudaelurus from Yepomera, MX
Pseudaelurus aeluroides from Yost Farm (Wood Mountain), CA
Pseudaelurus from Black Butte (UO 2343) (Juntura), US
Pseudaelurus from Cedar Mountain (Esmeralda), US
Pseudaelurus from Fish Lake Valley (Esmeralda), US
Pseudaelurus from Juniper Creek (UO 2451), US
Pseudaelurus from Red Basin (UO 2495) (Butte Creek Volcanic Sandstone), US
Pseudaelurus intrepidus from Tonopah, US
Pseudaelurus intrepidus from Avawatz Mountains (Avawatz), US
Pseudaelurus from Kent Quarry (DS Caliente), US
Pseudaelurus validus from Nambe (Tesuque), US
Pseudaelurus from Quatal Canyon South Side 3 (MR Caliente), US
Pseudaelurus from Wikieup (Big Sandy), US
Pseudaelurus from Adam Risley Ranch, US
Pseudaelurus from Screw Bean (Banta Shut-In), US
Pseudaelurus quadridentatus from Przeworno 1, Lower Silesia, PL
Pseudaelurus lorteti from Przeworno 2, Lower Silesia, PL
Pseudaelurus from Lufeng, Section D, Layer 2, CN
Pseudaelurus from Lufeng, Section D, Layer 3, CN
Pseudaelurus from Lufeng, Section D, Layer 4, CN
Pseudaelurus from Lufeng, Section D, Layer 5, CN
Pseudaelurus from Lufeng, Section D, Layer 6, CN
Pseudaelurus turnauensis from Al-Sarrar, Locality 8, Dam Formation (Dam), SA
Pseudaelurus from Panxian Dadong, CN
Pseudaelurus romieviensis from Langenau 1 (Brackwater Molasse), DE
Pseudaelurus from Bézian, FR
Pseudaelurus lorteti from Bézian, FR
Pseudaelurus romieviensis from Baigneaux-en-Beauce, FR
Pseudaelurus lorteti from Artenay, FR
Pseudaelurus from Zapfe's fissures, SK
Pseudaelurus lorteti from Sandberg, SK
Pseudaelurus turnauensis from Sandberg, SK
Pseudaelurus lorteti from Eggingen-Mittelhart 3 (Brackwater Molasse), DE
Pseudaelurus from Pellecahus, FR
Pseudaelurus quadridentatus from Pasalar, TR
Pseudaelurus from Pasalar, TR
Pseudaelurus lorteti from Antonios (Antonios), GR
Pseudaelurus quadridentatus from Antonios (Antonios), GR
Pseudaelurus from Isayevo, UA
Pseudaelurus aeluroides from Northeast Rim of Sinclair Draw (Olcott), US
Pseudaelurus from Ulaan Tologoi, UTO-A/5 (Loh), MN
Pseudaelurus intrepidus from Rhino Quarry (F:AM) (Sheep Creek), US
Pseudaelurus from Pellecahus, FR
Pseudaelurus intrepidus from Sharktooth Hill (terrestrial mammals) (Temblor), US
Pseudaelurus quadridentatus from Oggenhausen 2 (Upper Freshwater Molasse), DE
Pseudaelurus africanus from Rusinga Island, KE
Pseudaelurus africanus from Songhor (Main Site), KE
Pseudaelurus africanus from Karungu, KE
Pseudaelurus lorteti from Pontigne 3, FR
Pseudaelurus turnauensis from Pontigne 4 (marine), FR
Pseudaelurus lorteti from Pontigne 4 (marine), FR
Pseudaelurus from Grand-Trouve 4 (marine), FR
Pseudaelurus lorteti from Grand-Trouve 4 (marine), FR
Pseudaelurus romieviensis from Grand-Trouve 4 (marine), FR
Pseudaelurus marshi from UCMP V-99563 (Temblor), US
Pseudaelurus validus from Greenside Quarry (Sheep Creek), US
Pseudaelurus validus from Pliohippus Draw (Lower) (Sheep Creek), US
Pseudaelurus validus from Humbug Quarry (Olcott), US
Pseudaelurus validus from Far Surface Quarry (Olcott), US
Pseudaelurus validus from North Wall Quarry (Olcott), US
Pseudaelurus validus from Echo Quarry (Olcott), US
Pseudaelurus from Quatal Canyon South Side 14 (DSC Caliente), US
Pseudaelurus intrepidus from Sharktooth Hill (Temblor), US
Pseudaelurus from Princeton Loc. 1000C (Olcott), US
Pseudaelurus marshi from Observation Quarry, US
Pseudaelurus stouti from Observation Quarry, US
Pseudaelurus quadridentatus from En Pejouan, FR
Pseudaelurus quadridentatus from Malartic, a la ferme Larrieu, FR
class=notpageimage|
Location of Pseudaelurus grade fossils based on Paleobiology Database.[4]

Traditionally, all the Pseudaelurus-grade species from Europe, Asia, and North America have been assigned to a single genus, even though the paraphyletic nature of the group has often been noted. Several authorities have split Pseudaelurus into separate genera or subgenera, including Hyperailurictis, Styriofelis, Miopanthera and Schizailurus. These different groups of Pseudaelurus-grade felids are often considered to have given rise to later felid lineages.

The genus Styriofelis was originally proposed in 1929 by Kretzoi for the species Pseudaelurus turnaeunsis.[5] Kretzoi also proposed the genus Hyperailurictis for the North American species Pseudaelurus intrepidus,[6] and Miopanthera for Ps. lorteti.[7] In 1964, Beaumont elaborated on Kretzoi's proposal and split Pseudaelurus into three separate genera: Pseudaelurus for the European Ps. quadridentatus, Schizailurus for Ps. lorteti, and Hyperailurictis for Ps. intrepidus.[8]

Taxonomic history

[edit]

In 1843, the paleontologist H.M. de Blainville published a description of a felid cranium and lower jaw fragment from Sansan, France. He assigned these fossils to a new species, Felis quadridentata. The cranium was later reassigned to another species, but in 1850 the lower jaw fragment was assigned to a new genus by Paul Gervais as Pseudaelurus quadridentatus, due to having certain primitive features.[9]

In 1858, Joseph Leidy described the species Felis intrepidus, from North America, and reassigned the species as Pseudaelurus intrepidus in 1869. After that discovery, another eight species of Pseudaelurus would be described in North America, but only five are still considered valid.[2]

In 1872, Henri Filhol described the species Pseudaelurus edwardsi from France, but the species was reassigned to the nimravid genus Eofelis in 2000.[10]

In 1882, a second species from Europe was described as Pseudaelurus turauensis, and a third species, Pseudaelurus lorteti, in 1899. The fourth European species, Pseudaelurus romieviensis, was described in 1934. In addition, the species Pseudaelurus transitorius was described in 1892, but most later authors considered it a synonym of P. turnaeunsis.[2]

In 1914, fossils from Africa were described and assigned to the species Pseudaelurus africanus. However, the species was later reassigned, first to the genus Metailurus, and then finally to Afrosmilus.[11]

In Asia, the first description of Pseudaelurus was in 1910, when a fragmentary fossil was assigned to Pseudaelurus chinjiensis; however, it was reassigned in 1915 to the new genus Sivaelurus.[12] The next appearance of Pseudaelurus-grade felids in Asia wasn't until 1986, when a lower jaw fragment and some dental fragments were assigned to the species Pseudaelurus lorteti. In 1990, the species Pseudaelurus guangheensis was described.[13] In 1998, a second Asian species, Pseudaelurus cuspidatus, was also described.[14] Both of the Asian species are known only from fragmentary fossils.[2]

In 1998, while measuring fragmentary fossils from the Hsanda-Gol locality in Mongolia, Robert Hunt referred a lower jaw fragment to Proailurus sp.; while this was reassigned to the nimravid genus Eofelis in 1999 instead, a 2004 review of felid material from other localities in Mongolia suggested that it could belong to Pseudaelurus cuspidatus instead, on basis of having similar features. However, the Hsanda-Gol specimen is dated back to the Oligocene, while Pseudaelurus cuspidatus is found solely in Miocene-aged localities. The same paper also described a pair of fragments (a lower jaw fragment and a metapodial) and attributed them to Pseudaelurus sp.[12]

Restoration of P. quadridentatus by Mauricio Antón

In 2010, a review of the Felidae as a whole suggested that Pseudaelurus be split into three genera: Hyperailurictis for the five North American species, Styriofelis for two of the European species (P. lorteti and P. turnaunensis), and Pseudaelurus sensu stricto for P. quadridentatus. The status of P. romieviensis, P. guangheensis, and P. cuspidatus was given as uncertain. In addition, Miopanthera and Schizailurus were recognized as junior synonyms of Styriofelis.[8]

In 2012, a new species Styriofelis vallesiensis was described based on a specimen found in Spain.[15] However, a review of the species in 2017 concluded that it was sufficiently different from other Styriofelis species as to require a separate genus. It was thus reassigned to the new genus Leptofelis as Leptofelis vallesiensis.[16]

In 2017, a review of the species Felis pamiri, which was named based on a snout fragment from Turkey and dated to the late Miocene, concluded that Felis pamiri and Pseudaelurus lorteti were likely closely related to each other, and ancestral to the Panthera lineage. Both species were reassigned to the genus Miopanthera as Miopanthera lorteti and Miopanthera pamiri.[17]

Phylogeny

[edit]

The following cladogram is based on Piras et al. (2013)[18] and illustrates the three more derived lineages that evolved from "Pseudaelurus" species.

Felidae
†Proailurus
Proailurinae

†Proailurus bourbonnensis

†Proailurus lemanensis

†Proailurus major

"Pseudaelurus"
Pseudaelurus lineage
†Pseudaelurus

†Pseudaelurus quadridentatus

†Pseudaelurus cuspidatus

†Pseudaelurus guangheensis

†Machairodontinae

†Hyperailurictis
Hyperailurictis lineage

†Hyperailurictis intrepidus

†Hyperailurictis marshi

†Hyperailurictis stouti

†Hyperailurictis validus

†Hyperailurictis skinneri

†Sivaelurus

†Sivaelurus chinjiensis

Styriofelis lineage
†Styriofelis

†Styriofelis turnauensis

†Styriofelis romieviensis

Felinae

Felinae

†Miopanthera

†Miopanthera lorteti

†Miopanthera pamiri

Pantherinae

sensu lato
(grade)

Description

[edit]

Pseudaelurus quadridentatus weighed about 30 kg (66 lb) and was approximately the size of a cougar.

Distribution

[edit]
Restoration of Pseudaelurus (in tree at upper right) and other animals of the Mascall assemblage

Pseudaelurus guangheensis from the middle Miocene of Gansu (China) and Pseudaelurus cuspidatus from the middle Miocene of Xinjiang (China) are reported.[2]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Pseudaelurus

View on Grokipedia
from Grokipedia
Pseudaelurus is an extinct of early felids in the subfamily , representing a paraphyletic grade of primitive cats that lived during the epoch across , , and . Known from remains dating to approximately 18–10 million years ago (European Mammal Neogene zones MN4–MN9), the includes species such as the P. quadridentatus and the smaller P. romieviensis, which exhibit slender to robust mandibular and dental morphologies adapted for carnivory. These cats were generally small to medium-sized, with body plans resembling modern felines but retaining primitive features like a variable presence of the second upper (P2) and reduced m1 talonids. Pseudaelurus holds significant evolutionary importance as a stem group from which the modern cat subfamily () and the extinct saber-toothed cats () diverged, marking a key transitional phase in felid radiation. Fossils from , including partial skeletons from Early sites like the Namb Member of the Tesuque Formation in , provide the earliest evidence of the in the and reveal details of limb morphology, such as a functional first metatarsal in the pes.

Discovery and nomenclature

Etymology

The genus name Pseudaelurus derives from the words pseudes (ψευδής), meaning "false," and ailouros (αἴλουρος), meaning "," highlighting its resemblance to felids while possessing more primitive traits suggestive of an early evolutionary stage in cat development. The name was established by French paleontologist Paul Gervais in to accommodate fossils that did not fit neatly within the Felis. The , Pseudaelurus quadridentatus, was designated based on a partial mandible from the locality of Sansan, , originally described by in 1843 as Felis quadridentata in his work Ostéographie. Gervais's reassignment to a new emphasized the specimen's distinct dental morphology, including four prominent cusps on the lower tooth, which contributed to the "quadridentatus" (Latin for "four-toothed").

Key fossil discoveries

The genus Pseudaelurus was first recognized from jaw fragments discovered in 1843 at the Miocene site of Sansan in , , by paleontologist , who described them as Felis quadridentata; these remains, including a lower , formed the basis for the genus established by François Louis Paul Gervais in 1850. This initial find, dated to approximately 13.5–13 million years ago (MN 6 biozone), provided early evidence of the primitive felid's and marked the beginning of systematic study of Miocene cats in . Fossils of Pseudaelurus first appeared in around 18.5 million years ago, signaling the end of the "cat gap"—a roughly 7-million-year period (from 25 to 18.5 Ma) with scant felid remains on the continent following the extinction of earlier proailurines. These earliest n specimens, representing the genus's migration from via , include dental and cranial fragments from late Hemingfordian sites in and , such as the Marsland Formation and Lower White River Group exposures. Key localities like Big Spring Canyon in Sioux County, , yielded isolated teeth and postcranial elements attributed to P. skinneri, illuminating the rapid dispersal and adaptation of these cats in hemimarginal faunas. Further west, the Mascall Formation in Oregon's John Day Basin produced additional mandibular and dental fossils around 14–12 Ma (early to middle Barstovian), contributing to understandings of regional variation in Pseudaelurus morphology. In , significant discoveries include specimens of P. cuspidatus from the middle (approximately 16–14 Ma) Halamagai Formation in northern Uyghur Autonomous Region, , described in 1998 based on a mandible and upper fourth premolar from the Ulungur River area; these remains highlight the genus's diversity in arid continental settings. Similarly, P. guangheensis was identified from middle deposits (around 15 Ma) in Guanghe County, Province, , with fossils including mandibular fragments from the Dalanggou locality, underscoring Pseudaelurus's broad Eurasian range during the Langhian stage. In 2003, Rothwell described a new species, P. skinneri, based on mandibular and dental remains from the late Hemingfordian Sheep Creek Formation in , highlighting early diversity and morphological variation in North American Pseudaelurus. Across the Atlantic, 2013 excavations at the Abocador de Can Mata site in the Vallès-Penedès Basin, (dated to 11.9–11.6 Ma, middle ), uncovered jaw and dental remains of P. romieviensis and P. quadridentatus, including a possible second lower in the former, enhancing resolution of European species diversity and dental evolution.

Physical description

Body size and morphology

Pseudaelurus species exhibited a wide range of body sizes, from wildcat-sized individuals weighing approximately 5-10 kg in smaller forms like P. stouti to larger species approaching dimensions, with P. quadridentatus estimated at up to 33 kg. For instance, P. validus had an estimated body mass of about 26 kg, positioning it between a large and a small puma. The overall body plan was characterized by a slender, gracile build with an elongated body and a longer vertebral column than in modern felids, contributing to a low-slung posture. Legs were relatively short and viverrid-like, with shorter metapodia and metacarpals compared to extant cats, indicating a primitive morphology adapted for rather than sustained speed. A long, flexible tail likely aided balance during movement. Locomotor adaptations included a flexible spine enabling versatile motion, semi-retractable claws for grasping, and limb proportions suited for climbing and pouncing, as evidenced by partial skeletons from North American sites showing robust forelimbs and stance with functional first metatarsals. In some species like P. intrepidus, longer metacarpals and tibiae approached modern felid proportions, enhancing pouncing capabilities. Morphologically, Pseudaelurus resembled modern lynx or small pantherines in overall proportions but retained more primitive traits, such as less elongated distal limb segments, distinguishing it from fully cursorial modern cats.

Cranial and dental features

The skull of Pseudaelurus features a high and thin sagittal crest with prominent nuchal crests, providing attachment sites for strong jaw muscles, similar to the earlier Proailurus lemanensis. The facial region is shortened relative to earlier felids, an adaptation associated with maintaining high bite force in a hypercarnivorous diet. It retains the alisphenoid canal, a primitive feature lost in modern felids, while the braincase shows transitional characteristics between early feliforms and crown-group Felidae. Dentition in Pseudaelurus typically follows the modern felid of 3.1.3.1/3.1.2.1, totaling 30 teeth, though some exhibit variations such as the presence of an additional . Incisors are reduced in size, canines are conical without saber-like elongation, and are highly sectorial. The pair (upper P⁴ and lower m₁) is specialized for shearing meat, with an elongated trigonid on m₁ comprising at least 70% of its length and a reduced metaconid; postcarnassial molars are vestigial or absent. Upper P⁴ features a prominent protocone, and lower p₃/p₄ often bear posterior accessory cusps. Sensory adaptations include auditory bullae with a thick ectotympanic and enlarged caudal entotympanic, resembling those of and modern felids to support enhanced hearing. Species variations in cranial and dental features reflect size and regional differences; for example, P. quadridentatus from displays more robust jaws and occasionally retains a fourth upper (P¹), contrasting with smaller Asian species like P. lorteti that show reduced talonids on m₁. North American P. validus has a longer canine-to-p₃ and larger overall dentition compared to P. marshi.

Distribution and ecology

Temporal and geographic range

Pseudaelurus first appeared in the late early , with the earliest fossil records dating to approximately 20 million years ago (Ma) in , and persisted until the late , with the latest records around 8 Ma in . The temporal range corresponds to the MN3 to MN9 mammalian zones in (roughly 20–10 Ma), the late Hemingfordian to late Hemphillian in (approximately 18.5–6 Ma), and equivalent intervals in such as the Xiejian to Shangwangian stages. In , records are restricted to the early MN4a zone, around 16 Ma. The genus originated in , where it was widespread across and during the early to middle . In , significant fossils have been recovered from sites such as La Grive-Saint-Alban in (MN 7+8, ~12.5 Ma) and Epplesheim in (late , ~10 Ma). Asian occurrences include the Linxia Basin in China's Province, yielding species like P. guangheensis from middle deposits (~15–11.6 Ma). Pseudaelurus dispersed to via the Bering land bridge around 18.5 Ma during the late Hemingfordian, marking the end of a 7-million-year "cat gap" in the continent's felid fossil record that had persisted since the late extinction of earlier carnivorans like nimravids. fossils are primarily from the region, including formations in (e.g., Sheep Creek and Valentine), , , and , spanning the late Hemingfordian to late Hemphillian (up to ~7–6 Ma at sites like Edson Quarry, ). Limited African presence is evidenced by remains from the Al-Sarrar locality in , but no fossils have been documented from . By the , around 8 Ma, Pseudaelurus underwent gradual replacement by more derived felids, coinciding with the radiation of modern felid lineages across and . This transition reflects broader evolutionary shifts in carnivoran guilds during the closing .

Habitat preferences and diet

Pseudaelurus species primarily inhabited forested and woodland environments across during the , as evidenced by fossil assemblages from sites like La Grive-Saint-Alban in , where associated including cervids (deer) and small suggest dense, vegetated paleoecologies with humid conditions conducive to arboreal and predation. In , early fossils from formations such as the Tesuque in indicate woodland habitats, reflecting early conditions amid broader climatic transitions from closed forests to grasslands. Morphological features, including relatively short limbs and a flexible , point to arboreal capabilities, enabling and perching in trees for hunting in these humid, vegetated settings, while also allowing versatility in transitional mixed habitats. Pseudaelurus exhibited a hypercarnivorous diet, preying primarily on small to medium-sized mammals such as rabbits and , along with birds and possibly reptiles, as inferred from the shearing specialized for flesh-tearing rather than bone-crushing. Dental morphology shows reduced talonids on the lower first molar, consistent with a meat-focused feeding strategy and no reliance on scavenging. Ecologically, Pseudaelurus served as a mid-tier predator in food webs, targeting smaller herbivores in resource-partitioned niches alongside larger carnivores, thereby helping to regulate prey populations in forested and ecosystems prior to the radiation of more specialized felid lineages.

Taxonomy

Valid species

The genus Pseudaelurus includes a small number of valid species, recognized based on diagnostic dental features such as count, cusp morphology, and dimensions, alongside variations in body size and mandibular robusticity. Recent taxonomic revisions have consolidated the genus to approximately three to five accepted species, focusing on type material and key fossils while excluding junior synonyms and reassigned taxa. The type species, P. quadridentatus, was described from a dentary fragment collected in Sansan, France, dating to the middle Miocene (approximately 13–11 Ma). It exhibits a robust build comparable to a modern cougar (Puma concolor), with four upper premolars (P1–P4) and a strong, shearing carnassial (P4/m1) adapted for hypercarnivory. Fossils attributed to this species are known from European localities. P. cuspidatus represents the primary middle record from , based on a partial and isolated P4 from the Halamagai Formation in northern , (approximately 16–14 Ma). This smaller species, with an estimated body mass under 20 kg, features tall, narrow premolars with prominent, pointed cusps and a reduced P4 protocone, indicating a more primitive felid suited to versatile predation. The earliest Asian representative, P. guangheensis, is known from mandibular fragments in the Linxia Basin of Gansu Province, , dated to the early Middle (approximately 16 Ma). This species displays primitive , including a relatively unreduced metaconid on m1 and smaller overall tooth size, reflecting an early stage in felid diversification in eastern . P. romieviensis, a smaller species from middle Miocene European sites such as La Grive, (approximately 13–11 Ma), exhibits slender mandibular and dental morphologies adapted for carnivory.

Synonymy and revisions

In the , Pseudaelurus was established as a broad taxonomic category encompassing numerous Miocene felid fossils from and , functioning as a for a diverse array of small to medium-sized species that lacked clear distinguishing features at the time. This lumping reflected limited understanding of felid diversity, with many specimens assigned to Pseudaelurus based on superficial similarities in dentition and cranial morphology rather than phylogenetic relationships. Significant taxonomic revisions began in the early , culminating in a major overhaul by Werdelin et al. in 2010, who proposed splitting the traditional Pseudaelurus into three distinct genera to better reflect evolutionary lineages: for European species like S. turnauensis, characterized by specialized postcranial adaptations; for smaller Eurasian forms, including some North American migrants; and for larger African and Asian taxa, such as M. pampeana. This reclassification addressed the paraphyletic nature of Pseudaelurus by emphasizing differences in body size, limb proportions, and dental traits derived from comparative analyses of fossil material. Further refinements followed, including the 2017 reassignment of Pseudaelurus pamiri—originally described from Upper Turkish fossils—to pamiri by Peigné et al., based on its larger size, reduced canines relative to earlier congeners, and early pantherine-like features in the upper . Several genera and species have been proposed as synonyms or junior taxa within the historical scope of Pseudaelurus, including Metailurus (a machairodontine with serrated sometimes conflated with pseudaelurine forms) and Machaerodus minor (a smaller variant reassessed as congeneric in early descriptions). Debates persist regarding North American representatives, particularly Pseudaelurus skinneri from late Hemingfordian sites in , which Rothwell (2003) upheld as valid due to its distinct mandibular robusticity and coronoid process morphology, though some later studies question its separation from Hyperailurictis validus amid ongoing synonymy discussions. Today, Pseudaelurus is regarded as a paraphyletic grade rather than a monophyletic , serving as an ancestral stem to both modern felines and extinct sabertooths, with its redistributed across multiple lineages. Recent 2020s research, including CT scans of cranial endocasts and postcrania from sites like Abocador de Can Mata, continues to refine boundaries by revealing subtle variations in morphology and occlusal wear patterns, potentially resolving lingering ambiguities in Eurasian taxa.

Phylogeny

Evolutionary relationships

Pseudaelurus is recognized as a basal member of the family, occupying a stem position in the evolutionary lineage following the earliest known felid, , which appeared around 25 million years ago during the . This genus represents a paraphyletic grade-group of early felids that bridges the gap between primitive forms like and the more derived crown-group , encompassing ancestors to both modern subfamilies and extinct lineages such as the saber-toothed . Cladistic analyses have consistently placed Pseudaelurus as the sister taxon to the crown , with its diversification occurring in the early to middle prior to the major subfamily splits. Recent phylogenetic studies, including those utilizing Bayesian frameworks and fossil-calibrated trees, support this positioning, highlighting that North American species of Pseudaelurus form a basal relative to the subsequent Eurasian radiation that gave rise to modern felid diversity. The divergence of from the crown (Felinae and ) occurred around 22-18 Ma, with the subsequent split between and Felinae estimated between approximately 15 and 10 million years ago, marking the end of the Pseudaelurus grade and the onset of specialized felid radiations. Key synapomorphies uniting Pseudaelurus with derived felids include the reduction and loss of certain teeth, such as the absence of the first lower premolar (p1) and second lower molar (m2), alongside the specialization of the carnassial complex (P4/M1) for enhanced shearing efficiency and the presence of an extra lower premolar (p2) retained from more primitive ancestors. These dental adaptations reflect early trends toward the hypercarnivorous morphology characteristic of Felidae. Regarding outgroups, Pseudaelurus shares some superficial similarities with the extinct Nimravidae (false saber-tooths), such as overall body plan, but is firmly classified as a true felid based on distinguishing basicranial and dental features, including a cupped paroccipital process and expanded caudal entotympanic.

Role in felid evolution

Pseudaelurus represents a paraphyletic grade that served as a crucial ancestral group for the family, emerging in the Early around 20 million years ago (Ma) as a successor to the earlier and filling a pivotal niche in the post-Oligocene "" period by initiating the radiation of more derived felids, with fossils indicating a temporal range from approximately 20 to 8 Ma. This grade likely encompasses the last common ancestor to all modern felids, with key species such as P. turnauensis and P. lorteti giving rise to the conical-toothed around 14–13 Ma, while others like P. quadridentatus contributed to the origins of the extinct saber-toothed during the same timeframe. Its widespread distribution across and facilitated early diversification, bridging primitive felid forms to the specialized subfamilies that dominated subsequent carnivoran guilds. The adaptations of Pseudaelurus, including a versatile with limb proportions and suited for varied prey, enabled its descendants to radiate into diverse habitats from forests to open woodlands during the climatic optimum. However, the decline of this ancestral grade around 11.6–9 Ma coincided with post-Middle cooling, habitat shifts toward grasslands, and increased competition from emerging canids and other carnivorans, leading to elevated rates and paving the way for more specialized felid lineages. This turnover marked a critical transition, where Pseudaelurus's foundational traits influenced the evolutionary success of later felids amid environmental pressures. As a body plan template, provided the skeletal blueprint—such as robust humeri with deltoid ridges and feet—that persisted for approximately 20 million years, influencing modern felids through intermediate morphologies comparable to lynx-sized cats in overall structure and moderate cursoriality. Skeletal studies highlight its legacy in balancing power and agility, with limb features echoing the foundational designs seen in extant like pumas for versatile predation, though lacking extreme specializations for speed (as in ) or (as in tigers). This enduring template underscores 's role in shaping the biomechanical diversity of over geological time. Despite its importance, gaps in the fossil record, including fragmentary remains and limited genetic data, hinder precise resolution of branching events within Pseudaelurus, complicating exact phylogenetic ties to modern lineages. Recent analyses, calibrated through genomic and mitochondrial data, continue to affirm its origins around 20 Ma, with subfamily divergences estimated at 22–18 Ma, though ongoing refinements are needed to integrate sparse evidence.

References

  1. https://www.sciencedirect.com/science/article/pii/S1631068313000213
  2. https://www.researchgate.net/publication/232691771_Phylogenetic_Systematics_of_North_American_Pseudaelurus_Carnivora_Felidae
  3. https://digitallibrary.amnh.org/items/95f9c37f-73c4-4161-9bb0-26f5b580ea9a
  4. https://digitalcommons.unl.edu/context/natlpark/article/1148/viewcontent/Agate_Fossil_Handbook_1980.pdf
  5. https://digitallibrary.amnh.org/bitstreams/d871f9b1-1068-46f0-b917-431099434d02/download
  6. https://npshistory.com/publications/joda/nrr-2014-846.pdf
  7. https://www.researchgate.net/publication/267156816_Carnivora_from_middle_Miocene_of_Northern_Junggar_Basin_Xinjiang_autonomous_region_China
  8. https://digitallibrary.amnh.org/bitstreams/ad3b6a34-348c-4456-916a-b764bc3364fb/download
  9. https://www.researchgate.net/publication/233346740_Correlation_of_carnassial_tooth_size_and_body_weight_in_Recent_carnivores_Mammalia
  10. https://www.geokniga.org/bookfiles/geokniga-thebigcatsandtheirfossilrelativesanillustratedguidetotheirevolutionandnatur.pdf
  11. https://www.researchgate.net/publication/232687955_A_Partial_Skeleton_of_Pseudaelurus_Carnivora_Felidae_from_the_Namb_Member_of_the_Tesuque_Formation_Espaola_Basin_New_Mexico
  12. https://repository.lib.fsu.edu/islandora/object/fsu:182188/datastream/PDF/download
  13. https://pmc.ncbi.nlm.nih.gov/articles/PMC11791394/
  14. https://onlinelibrary.wiley.com/doi/10.1111/pala.12296
  15. https://www.vertpala.ac.cn/EN/Y1998/V36/I03/218
  16. https://www.sciencedirect.com/science/article/abs/pii/S0031018223000810
  17. https://hal.sorbonne-universite.fr/hal-01675275/document
  18. https://www.researchgate.net/publication/369118720_First_fossil_of_Styriofelis_Felidae_Carnivora_from_the_Middle_Miocene_of_the_Madrid_Basin
  19. https://pubmed.ncbi.nlm.nih.gov/35098251/
  20. https://www.biorxiv.org/content/10.1101/2023.06.29.547091v1.full.pdf
  21. https://pmc.ncbi.nlm.nih.gov/articles/PMC7612286/
  22. https://www.researchgate.net/publication/266755142_Phylogeny_and_evolution_of_cats_Felidae
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