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Asilifelis
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Asilifelis
Temporal range: Burdigalian
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Felidae
Genus: †Asilifelis
Werdelin, 2012
Type species
†Asilifelis coteae
Werdelin, 2012

Asilifelis is an extinct genus of small felid that lived in what is now Kenya during the Early Miocene. Despite its fragmentary remains, it is remarkable because of its small size and advanced dentition. It contains a single species, Asilifelis cotae.[1]

Discovery and naming

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Asilifelis is only known from a single specimen: KNM RU 18349, a mandibular ramus, including the well-preserved teeth p4-m1, which is stored in the National Museums of Kenya. The fossil was discovered in rocks of the Hiwegi Formation on Rusinga Island in 1949, but was subsequently only mentioned once in scientific literature until its description by Lars Werdelin in 2012.

The generic name is a combination of Swahili asili ("origin") and Latin felis ("cat"). The species name "coteae" honors Susanne Cote, who inspired Werdelin's interest in Miocene Africa.[1]

Description

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Asilifelis is much smaller than other Early Miocene felids, comparable in size to the smallest extant species,⁣[1] such as the rusty-spotted cat, which weighs around 1-1.6 kg.[2] Furthermore, its dentition is extremely modern in comparison to contemporary felids, being transitional between "Pseudaelurus-grade" and modern species. It possesses a slender p4, with a prominent cingulum and a tall main cusp, with a relative height greater than that of most extant and all coeval felids, comparable to that of the black-footed cat. The distal and mesial accessory cups are relatively low, whereas other Early Miocene cats possess larger accessory cups, which are more distinctly set off from the main cusp. However, they are also less appressed to the main cup than those of modern felids. The m1 is much taller than the premolar, although relatively shorter than in "Pseudaelurus-grade" forms, with strongly developed protoconid and paraconid. Both the anterior of the paracristid and posterior of the protocristid are nearly vertical. The talonid is noticeably reduced, being short and very low, while the metaconid is entirely absent. The distal end of the tooth possesses a short cingulum, which extends along its lingual side to the paraconids distal end. The p4 and m1 are somewhat overlapping.[1]

Evolutionary context

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Most felids of the Burdigalian belong to a diversification of the so-called "Pseudaelurus-grade", basal species with primitive features, which are thought to have given rise to modern genera, with modern "Felis-grade" felids such as Pristifelis not appearing until 11.6 Ma. Therefore, the existence of a felid as derived as Asilifelis in Early Miocene rocks is surprising. It is possible that this African lineage was forced into a hypercarnivorous role much earlier than their Eurasian relatives due to competition with abundant viverrids and herpestids. It has also been speculated that it gave rise to modern felids, which could perhaps explain the sudden appearance of modern felines at the start of the Late Miocene in Eurasia. However, the limited material makes these conjectures impossible to confirm. Fossils of other Early Miocene African felids are limited, and mostly represented by the much larger "Pseudaelurus-grade" genera Diamantofelis and Namafelis. The distant relationship between these forms and Asilifelis potentially suggests two separate dispersal events of felids into Africa during the Early Miocene.[1] Furthermore, Katifelis nightingalei, another species with similar transitional features, was described from slightly younger rocks of the Kenyan Lothidok Formation in 2018.[3] Other felids are not known from the continent until the sudden appearance of forms such as Machairodus around 12.5 Ma. An explanation for this gap in the fossil record might be that they primarily inhabited poorly sampled habitats, or alternatively were excluded from these ecosystems by the diversity of small viverrids and herpestids.[1]

Paleoecology

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The Fossil Bed Member of the Hiwegi Formation, where Asilifelis was found, likely represents a woodland or mosaic forest.[4] The fossil assemblage is rich and includes a high diversity of rodents from various families,[5][6] as well as other small mammals such as tenrecs, elephant shrews and hedgehogs. Carnivores of similar size to Asilifelis are represented by the viverrids Herpestides and Kichechia,[5] and the hyaenodont Exiguodon,[7] while larger predators include the barbourofelid Afrosmilus,[3] the bear-dog Cynelos[8] as well as a variety of hyaenodonts such as Hyainailourus and Dissopsalis.[7] A large number of primates are also present, among them the early ape Ekembo. Asilifelis furthermore coexisted with a variety of rhinoceroses, proboscideans such as Prodeinotherium, several pig species, early giraffes[5] and the crocodylians Euthecodon and Brochuchus.[9]

References

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Asilifelis

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from Grokipedia
Asilifelis is an extinct of small felid (family Felidae) known from the Early of , representing one of the earliest and most diminutive members of the cat family. The genus contains a single , Asilifelis coteae, based on a specimen consisting of a right mandibular ramus preserving the fourth (p4) and first molar (m1), on in the Hiwegi Formation. This species exhibits a body size comparable to the smallest extant felids and dental features that bridge primitive "Pseudaelurus-grade" morphology with more derived traits seen in modern , such as a reduced talonid on m1 and absent metaconid. The name Asilifelis derives from the word "asili," meaning "origin" or "," reflecting its basal position in felid evolution, while the specific honors paleoanthropologist Susanne Cote. Dated to approximately 18–20 million years ago (lower to middle stage), A. coteae is the most derived felid from the lower in and suggests an early diversification of the Felinae subfamily on the continent. It differs from contemporaneous genera like in lacking an m2 and having a taller paraconid on m1, and from later forms such as in its less prominent p4 accessory cusp and fully reduced m1 metaconid. Comparisons with other early Miocene felids highlight Asilifelis's unique transitional status; for instance, it is smaller and less robust than the contemporaneous Kenyan genus Katifelis nightingalei from the Lothidok Formation. The fragmentary nature of the remains limits detailed anatomical reconstruction, but Asilifelis underscores the rapid evolutionary experimentation among early felids in , potentially influencing the of modern cats.

Discovery and naming

Discovery

The specimen of Asilifelis coteae was discovered in 1949 on , , within the Hiwegi Formation of the Rusinga Group. This formation dates to the Early , specifically the lower-middle stage, approximately 18–20 million years ago. The specimen, cataloged as KNM RU 18349, consists of a fragmentary right mandibular ramus preserving the complete fourth (p4) and first molar (m1). The was formally described in 2011 by paleontologist Lars Werdelin in Estudios Geológicos, establishing Asilifelis coteae as a new and of small felid based on these fragmentary remains. The description highlighted the specimen's significance as one of the earliest known felids in , though its limited preservation precluded extensive morphological analysis at the time. Geologically, the Hiwegi Formation comprises intercalated volcanic tuffs, sandstones, and pyroclastic deposits that reflect a dynamic influenced by nearby . These sediments indicate a mix of lacustrine and fluvial settings, with airfall tuffs and alluvial sands preserving a record of ancient lakes, rivers, and periodic landscape stability amid active eruptions from the Kisingiri complex.

Etymology

The genus name Asilifelis combines the Swahili word asili, meaning "origin" or "ancestor," which underscores the taxon's position as one of the earliest known felids in , with the Latin felis, denoting "cat." The species epithet coteae is a tribute to paleontologist Susanne Cote, recognized for her significant work on Miocene mammal faunas in , including fieldwork in regions like the Turkana Basin and Tugen Hills. This new genus and species, Asilifelis coteae gen. et sp. nov., was formally described by Lars Werdelin in 2011.

Physical characteristics

Size and build

Asilifelis coteae exhibited a diminutive body size, comparable to that of the modern (Prionailurus rubiginosus), with an estimated body mass ranging from 1 to 1.6 kg, rendering it the smallest known felid from the Early . This estimation is derived from the limited fossil material, consisting solely of a right mandibular ramus preserving the fourth (p4) and first molar (m1), through comparisons of dental dimensions to those of extant small felids. The slender proportions of the indicate a lightweight and agile skeletal build.

Dentition and cranial features

Cranial features of Asilifelis coteae are unknown, as no cranial material has been recovered; the known anatomy is limited to the dentition preserved in the holotype. The holotype of Asilifelis coteae (KNM-RU 18349) consists of a well-preserved right mandibular ramus bearing the lower carnassial teeth p4 and m1, recovered from the Early Miocene Hiwegi Formation on Rusinga Island, Kenya. The mandible exhibits a robust yet relatively gracile construction, with a deepened horizontal ramus beneath the carnassials indicative of a modern felid-like morphology adapted for forceful biting. The lower fourth (p4) is slender and elongated, measuring approximately 5.5 in and 2.4 in width, with a prominent cingulum, a tall main cusp exceeding the height of those in most coeval felids, and low accessory cusps that are less appressed to the main cusp than in extant species. The first lower molar (m1) is taller than p4, with a of about 7.4 and width of 2.8 ; it features a strong protoconid and paraconid, a nearly vertical anterior paracristid and posterior protocristid forming an efficient shearing blade, a reduced and short low talonid, and the complete absence of a metaconid, along with a short lingual cingulum. These traits reflect advanced hypercarnivorous adaptations, including a shortened tooth row optimized for meat shearing, distinguishing Asilifelis from more primitive proailurine felids. Overall, the dentition of Asilifelis coteae represents a transitional form between Pseudaelurus-grade felids and modern taxa, with its diminutive scale—evident in the small tooth dimensions—aligning with the genus's overall compact build.

Taxonomy and phylogeny

Classification

Asilifelis is an extinct genus of small felid within the family , order , superfamily . It contains a single , Asilifelis coteae, making it monotypic. The specimen, designated as KNM RU 18349, consists of a fragment of the right mandibular ramus preserving the complete p4-m1, collected from , . The genus and species were formally described and named in 2011, and it has been recognized as a valid without synonyms since its establishment. Subfamily placement for Asilifelis remains uncertain, with tentative assignment to a basal of rather than Proailurinae or any extant subfamilies.

Evolutionary relationships

Asilifelis coteae dates to the Early stage, approximately 18–20 million years ago, from the Hiwegi Formation on , , marking it as one of the earliest documented felids in . This temporal placement positions it among the initial radiation of felids into the continent following their dispersal from around 20 million years ago. Phylogenetically, A. coteae serves as a transitional between Pseudaelurus-grade felids, exemplified by , and modern crown-group , exhibiting a of primitive and derived features in its . Key derived traits include the complete absence of the m2, loss of the m1 metaconid, and a significantly reduced m1 talonid, which collectively indicate an early toward hypercarnivory by emphasizing shearing over grinding functions. These modifications distinguish it as more advanced than other early African felids like Diamantofelis ferox and Namafelis minor, from which it differs in the greater reduction of the m1 talonid. In comparisons to contemporaneous forms, A. coteae lacks the m2 and possesses a taller m1 paraconid relative to Proailurus, while showing a less prominent accessory cusp on p4 and no m1 metaconid compared to Styriofelis. It is substantially smaller than co-occurring larger carnivorans like Afrosmilus africanus from the same deposits, with which it shares the locality but differs in dentition aligned more closely with felid hypercarnivores than barbourofelid saber-tooths. Relative to the slightly younger Katifelis nightingalei from West Turkana (ca. 17 Ma), A. coteae exhibits less robust dentition and smaller overall size, yet both display similar intermediate traits bridging Pseudaelurus- and Felis-grade morphologies. The evolutionary significance of Asilifelis lies in its status as the most derived lower felid known, highlighting an early phase of small-bodied felid diversification in that may underpin the continental origins of several modern lineages.

Paleobiology and

Habitat and environment

Asilifelis was discovered in the Hiwegi Formation, located on in the Basin of western , which consists primarily of tuffaceous sandstones, volcaniclastic deposits, and associated fluvial and lacustrine sediments dating to approximately 18–20 million years ago during the early ( stage). This formation, part of a broader sequence influenced by eruptions from the nearby Kisingiri volcano, records a depositional history marked by episodic volcanic air-fall tuffs, reworked volcanic materials, and fluvial intercalations, with such as cross-stratified sandstones, laminated siltstones, and conglomerates indicating dynamic sediment transport. The paleoenvironment of the Hiwegi Formation represents a mosaic that included riverine woodlands, closed-canopy forests, and open grasslands or bushlands, as inferred from sedimentary , leaves, root traces, and tree-stump casts preserved across different members. Evidence from the Grit/Fossil Bed Member points to fluvial and ponded settings with sheet-flood and flash-flood events, while the overlying Kibanga Member shows transitions to more stable, vegetated areas with volcanic tuffs and paleosols. This heterogeneity reflects a dynamic interface between terrestrial and aquatic systems, shaped by seasonal flooding and volcanic activity that contributed to the deposition of coarse clastics and fine-grained overbank sediments. Climatic conditions during the deposition of the Hiwegi Formation were characterized by warm, humid subtropical environments with strong , featuring wet and dry periods that supported diverse C3-dominated vegetation, including trees, shrubs, climbers, and plants adapted to varying light and moisture levels. Inferences from paleosols, evaporitic features like mud cracks and tepee structures in lower sections, and pedogenic carbonates suggest initial drier phases with exceeding (likely <100 cm/year), transitioning upward to wetter conditions that fostered closed forests. carbon isotope analyses (δ¹³C values ranging from -30.9‰ to -9.4‰) further confirm a predominance of closed, forested habitats with minimal open C4 grasslands. Fossils of Asilifelis, including its , are preserved in lake margin deposits of the Fossil Bed Member, where rapid burial in fine-grained, volcaniclastic sediments at the aquatic-terrestrial interface facilitated exceptional taphonomic preservation, likely enhanced by the hyper-alkaline chemistry from volcanic inputs. This setting, with its mix of hypersaline ponds and fluvial channels, indicates that remains were transported short distances before entombment, minimizing post-mortem alteration in a geologically active basin.

Diet and associated fauna

Asilifelis coteae exhibited a hypercarnivorous diet, as evidenced by its , which features a reduced talonid on m1 and prominent teeth (p4 and m1) specialized for shearing flesh. This morphology indicates a reliance on prey, with the absence of a metaconid and short talonid minimizing bone-crushing capabilities and emphasizing meat consumption. The small body size of A. coteae, comparable to the smallest extant felids, suggests it occupied an that minimized competition with larger carnivorans, such as the ursid Hemicyon sp., by targeting smaller prey items within the . As a basal predator, it likely functioned as an opportunistic hunter in a trophic structure supported primarily by herbivorous mammals and punctuated by diverse small carnivores. In the Hiwegi Formation assemblage, A. coteae coexisted with a rich diversity of small mammals, including such as Ekembo hesloni, from multiple families, and other carnivorans like herpestids (Kichechia zamanae, Leptoplesictis mbitensis, Leptoplesictis rangwai), mustelids (Luogale rusingensis), and viverrids. This community composition reflects a complex with abundant potential prey and competitors, underscoring A. coteae's role in a multifaceted mammalian dominated by herbivores and mid-sized predators.
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