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Camelops
Temporal range: Middle Pliocene to Late Pleistocene, 3.2–0.013 Ma
↓
Mounted skeleton of Camelops hesternus in the George C. Page Museum, Los Angeles
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Camelidae
Subfamily: Camelinae
Tribe: Camelini
Genus: †Camelops
Leidy, 1854
Species

Camelops is an extinct genus of camel that lived in North and Central America from the middle Pliocene (from around 4-3.2 million years ago) to the end of the Pleistocene (around 13-12,000 years ago). It is more closely related to living camels than to lamines (llamas, alpacas, vicuñas, and guanacos), making it a true camel of the Camelini tribe. Its name is derived from the Ancient Greek κάμηλος (cámēlos, "camel")[1] and ὄψ (óps, "face"),[2] i.e. "camel-face". Camelops lived across Western North America, ranging from the Pacific Coast to the Great Plains, southwards to Honduras and northwards to Alaska. Camelops became extinct as part of the end-Pleistocene extinction event, along with most large mammals across the Americas. The extinctions followed the arrival of humans to the Americas, and evidence has been found indicating that humans butchered Camelops, suggesting that hunting may have been a factor in its extinction.

Taxonomy and evolution

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History of research

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Camelops was first named by Joseph Leidy in 1854, based on a partial maxilla (upper jawbone), that was found in a gravel drift somewhere in the Kansas Territory, with Leidy naming the type species Camelops kansanus in the same publication based on the maxilla. Later authors have judged that while the jawbone undoubtedly represents Camelops, it is too fragmentary to be diagnostic to species, making C. kansanus a nomen dubium. Later in 1874, Leidy named the species Camelops hesternus, based on teeth found in a gravel deposit in Arroyo Las Positas in Livermore Valley, Alameda County in the southern Bay Area of California. Several other species, including Camelops sulcatus named by Edward Drinker Cope in 1893 based on a partial left mandible, found at Rock Creek, Texas, as well as Camelops huerfanensis, named by Francis Whittemore Cragin in 1892 based on remains found along the Huerfano River in Colorado (as well as its claimed subspecies Camelops huerfanensis dallasi named by Richard Swann Lull in 1921 for remains collected along the Trinity River in northeast Texas), Camelops aransas named by Oliver Perry Hay in 1926 for remains including a partial right mandible found on a bank of the Aransas River in southeast Texas, and Camelops traviswhitei named by Mooser and Dalquist in 1975 from remains found in Aguascalientes in central Mexico, are now regarded as junior synonyms of C. hesternus.[3]

Another species, C. minidokiae, named by Hay in 1927 for jaw and teeth remains found in a gravel bed near Minidoka, Idaho, has been suggested to also be potentially valid, given its apparently smaller size than C. hesternus, though other authors have suggested that it is another synonym for C. hesternus. This species is primarily recorded during the Irvingtonian (Early-Middle Pleistocene), though some remains of the species have been reported from the Rancholabrean (late Middle-Late Pleistocene).[3]

Some scientific publications have used the informal names "western camel" and "yesterday's camel" for Camelops.[4][5]

Evolution

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The family Camelidae, which contains the living camels, as well as lamines (the tribe Lamini, which includes the llama, guanaco, alpaca and vicuña), first emerged in North America during the Eocene, around 46-42 million years ago, reaching its apex of diversity during the Miocene epoch (23-5.3 million years ago). The two modern tribes of Camelidae, Camelini and Lamini, are suggested to have diverged during this period, around 17.5-16 million years ago.[6] Living camels are thought to descend from Paracamelus, which crossed the Bering Land Bridge into Eurasia from North America during the Late Miocene, around 6 million years ago.[7] Although historically often assigned to Lamini,[3][8] ancient DNA obtained from Camelops indicates that it is a member of Camelini more closely related to living camels than to lamines, making it a true camel, with an estimated divergence from living camels around 11-10 million years ago.[6]

Phylogenetic relationships of Camelops compared to living and recently extinct camels, after Yuan et al. (2024).[9]

Camelidae

Lamini

Camelini

†Camelops hesternus

Camelus

Camelus dromedarius (dromedary)

†Camelus knoblochi

Camelus ferus (wild Bactrian camel)

Camelus bactrianus (domestic Bactrian camel)

The oldest fossils of Camelops are known from southern North America, dating to around 4-3.2 million years ago during the Pliocene epoch.[6] During the Pliocene and Early Pleistocene epochs (Blancan-Irvingtonian) other camels, such as Gigantocamelus, Blancocamelus, Titanotylopus and cf. Paracamelus were also present in North America,[8][10] but by the Late Pleistocene (Rancholabrean), Camelops represented the last remaining camel in the Americas.[6]

Description

[edit]
C. minidokae skull

Camelops hesternus was a large camel with a bodyform similar to a living dromedary, reaching a shoulder height of 2.3 m (7 ft 7 in)[11] with body mass estimates ranging from 437 kilograms (963 lb)[12] to 826 kilograms (1,821 lb),[13] to around 1,000 kilograms (2,200 lb),[11] though the size of the species was variable, with individuals known from the far north of the species range in Alaska and Yukon being considerably smaller than those from elsewhere.[14] Whether Camelops had humps or not like living camels is uncertain.[11] The skull has 1 incisor, 1 canine, 2 premolars and 3 molars in each half of the upper jaw, and 3 incisors, 1 canine, 1 premolar and 3 molars in each half of the lower jaw. The upper first premolar and both upper and lower second premolars are absent, with the lower first premolar usually absent and only occasionally present. The molar and premolar teeth are very high-crowned (hypsodont), with the molars being slender relative to their length, with the canines, upper third premolar and lower fourth premolar being reduced in size. The premaxilla bone is robust, with the rostrum of the skull being elongate, with the facial region of the skull not exhibiting considerable shortening. The nasal bones are strongly arched.[3] The brain is relatively large, estimated at 990 grams (2.18 lb).[13] The mandible is relatively deep. The limbs are relatively elongate (around 20% longer than those of living dromedaries[11]) but robust. The metapodial bones are robust and relatively short.[3]

Distribution, habitat and ecology

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Life restoration of C. hesternus

During the Pleistocene, Camelops is known from fossils across western North America, ranging from California, Oregon and Washington State, eastwards to South Dakota, Nebraska, Kansas, Oklahoma and Texas, with rarer records further east, including near the Missouri-Illinois border.[15][16] Southwards Camelops ranged to Honduras in Central America.[16] The northernmost records of Camelops are known from Alaska and Yukon, but it probably only occupied this region during warm interglacial intervals, before becoming extirpated from the region during glacial periods, as is thought for some other species whose remains are also rarely found in the region, such as the ground sloth Megalonyx jeffersoni, mastodons and Castoroides giant beavers.[17] Across its range it inhabited a wide variety of habitats, from subtropical environments,[6] to tundra,[11] though it seems to have primarily lived in open habitats.[18] In parts of its range Camelops hesternus co-occurred alongside the lamines Hemiauchenia and Palaeolama.[15]

An isotopic analysis study including specimens across the species range concluded that Camelops hesternus was a browser that consumed shrubbery, including species with a both a C3 and C4 type carbon fixation, as well as possibly those with Crassulacean acid metabolism.[15] A paired dental microwear and δ13C analysis of C. hesternus fossils from two sites in Mexico likewise revealed it to be a browser that fed on C3 and C4 vegetation alike.[19] Plants consumed by Camelops are suggested to include saltbrush (Atriplex),[15][20] a plant also commonly found in the diet of living camels.[20] Other studies have supported a browsing or mixed feeding diet for Camelops,[18][20][21] but a 2021 dental wear analysis study suggested that in some locations such as in Nebraska, Camelops hesternus engaged in grazing, sometimes predominantly so, suggesting that Camelops hesternus was a flexible feeder.[21]

Painting of animals around a lake
Environment of what is now White Sands National Park, with Camelops in the right background

Tracks found in Alberta, Canada suggest that like living camels, Camelops probably lived in herds, which like living camels may have been led by a dominant adult male.[22] Isotopic analysis suggests that Camelops may have engaged in seasonal migrations.[15] As in living camels, Camelops may have had a slow reproductive rate, including giving birth to a single offspring at a time, as well as existing at relatively low population densities due to its large size.[18] Camelops hesternus was probably predated upon by large carnivores, which during the Late Pleistocene may have included dire wolves (Aenocyon dirus)[23] the sabertooth cat Smilodon fatalis,[24] the scimitar-toothed cat (Homotherium serum)[25] and the American lion (Panthera atrox).[26] Specimens of Camelops have been found exhibiting signs of disease like osteoarthritis.[27]

Relationship with humans and extinction

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Camelops went extinct around 13-12,000 years ago as part of the end-Pleistocene extinction event along with most other large mammals across the Americas. These extinctions followed the arrival of humans to the Americas, and it is suggested that human hunting may have had a contributory role in the extinctions (though some authors have argued that climatic change was the most important factor[5]). At Wally's Beach in Alberta, Canada, butchered remains of Camelops hesternus displaying cut and fracture marks, alongside those of caballine true horses are associated with stone tools, with the site radiocarbon dated to around 13,300 years ago. This represents the only confirmed Camelops butchery site. The site was originally attributed to the Clovis culture based on the similar timing as well as findings of unassociated Clovis points within the local area, but the site does not display clear evidence of Clovis-type tools.[28] Some authors have suggested that fractured bones of Camelops found near Casper, Wyoming (which also represent the youngest well-dated remains of the species, dating to around 13,060 years Before Present[11]) may represent a butchery site, but this is not definitive.[29] Other possible, but not definitive sites where Camelops remains may be associated with human activity include Carter/Kerr-McGee and Colby sites in Wyoming (the latter of which is associated with a Clovis point) and the Lehner site in Arizona.[30] A sacrum of Camelops found near Tequixquiac in central Mexico has been suggested to have been shaped to resemble an animal head.[31]

See also

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia

Camelops

View on Grokipedia
from Grokipedia
Camelops was an extinct genus of large, camel-like artiodactyls in the family Camelidae, subfamily Camelinae, and tribe Camelini, closely related to modern Old World camels (Camelus) and distinct from South American lamoids.[1] These robust herbivores, with the type species Camelops hesternus, evolved in North America during the late Pliocene approximately 4–3 million years ago and persisted until the end of the Pleistocene, when they became part of the broader megafaunal extinction event around 13,000 years ago.[2][1] Standing about 7 feet (2.1 meters) tall at the shoulder and weighing up to 1,800 pounds (800 kilograms), Camelops was one of the largest camelids native to the continent, featuring a long neck, two-toed hooves adapted for arid terrains, and a body form reminiscent of a dromedary but without confirmed humps.[2] Fossils indicate a wide distribution across North America, from Alaska and Yukon in the north to Mexico in the south, inhabiting diverse environments including grasslands, open woodlands, and wetlands during both glacial and interglacial periods.[2][3] As browsers, they primarily fed on shrubs and vegetation such as saltbush (Atriplex sp.), often living in small herds similar to modern camels.[2] Phylogenetically, Camelops diverged from the lineage leading to Camelus during the Late Miocene (17.5–7 million years ago), originating in North America after the family's dispersal across the Bering Isthmus, and representing the final large camelid genus on the continent before its extinction.[1] The genus's disappearance, alongside other Pleistocene megafauna, is attributed to a combination of climate change at the end of the Ice Age and human hunting pressures, as evidenced by archaeological sites showing direct predation on Camelops individuals.[1][2] High-latitude populations in Alaska and Yukon were notably smaller than southern ones, conforming to Bergmann's rule, and fossils from these regions suggest they occupied northern areas primarily during warmer interglacial intervals.[3]

Taxonomy

Classification

Camelops belongs to the family Camelidae, subfamily Camelinae, and tribe Camelini, which aligns it phylogenetically with Old World camels (genus Camelus) rather than the tribe Lamini that encompasses New World camelids such as llamas (Lama), alpacas (Vicugna pacos), and guanacos (Lama guanicoe). This placement is supported by molecular evidence indicating that Camelops diverged from the lineage leading to Eurasian camels in the Late Miocene and is more closely related to them than to South American lamines.[4] The genus Camelops was established by American paleontologist Joseph Leidy in 1854, with the name derived from Greek kamelos (camel) and ops (face), reflecting the resemblance of its cranial morphology to that of extant camels. Leidy's description was based on fragmentary remains, including a partial maxilla from the Kansas Territory, highlighting early recognition of its camel-like features. Over time, the nomenclature has seen revisions, including synonymies and reassignments. The type species is Camelops kansanus Leidy, 1854, designated from the aforementioned maxillary fragment, though it is now regarded as a nomen dubium due to insufficient diagnostic material. Subsequent taxonomic work has recognized additional species within the genus, with mergers and synonymies reducing the number of valid taxa from over a dozen proposed names; notable revisions include the consolidation of forms like Camelops sulcatus and Camelops huerfanensis under C. hesternus. These changes stem from comprehensive osteological analyses that emphasize consistent generic characters across Pleistocene specimens.[5][3] At the genus level, Camelops is diagnosed by several key features, including highly hypsodont (high-crowned) cheek teeth suited for abrasive vegetation, with a dental formula of I 1/3, C 1/1, P 2/1, M 3/3, featuring reduced incisors and premolars, slender molars, and minimal external styles. Cranially, it exhibits an elongated, slender rostrum, robust premaxillae, a deep maxillary fossa, large lacrimal vacuities, and strongly arched nasals, contributing to a facial structure reminiscent of modern camels. These traits, combined with a deep mandible and small angular process, distinguish Camelops from other camelids while underscoring its adaptations as a large, North American grazer with evolutionary roots on the continent.[5]

Species

The genus Camelops is currently recognized to include two valid species from the Pleistocene of North America: C. minidokae and C. hesternus. These species differ primarily in postcranial morphology, with C. hesternus representing the more widespread and later-occurring form. Camelops hesternus, the western camel, originally described from the Rancholabrean (Late Pleistocene) of Arroyo Las Positas, Alameda County, California. It is characterized by larger body size and robust, elongate metapodials adapted to open habitats, with metacarpal lengths ranging from 374–380 mm. Fossils of this species are abundant in western North America, including key sites such as Rancho La Brea in California, where hundreds of specimens have been recovered, as well as localities in New Mexico, Texas, and central Mexico. Eastern occurrences, such as in Texas gravel pits, indicate a broad distribution across the continent's western and central regions. In contrast, Camelops minidokae is a smaller species known primarily from the Irvingtonian (Middle Pleistocene), with a more restricted range in the Great Basin and California. It features shorter and more slender metapodials, including a humerus of about 350 mm and a tibia of 470 mm, suggesting adaptations for less open environments compared to C. hesternus. Key fossils come from sites like Minidoka, Idaho, and Irvington, California. Some researchers have debated whether C. minidokae represents a distinct species or a junior synonym of C. hesternus based on overlapping dental traits, but postcranial differences support its separation. Taxonomic synonymy within Camelops remains contentious, with numerous nominal species proposed historically based on limited material. For C. hesternus, junior synonyms include C. sulcatus, C. huerfanensis, and C. traviswhitei, resolved through comparisons of metapodial proportions and enamel patterns. Debates persist over potential additional species or subspecies, particularly those with short, broad metapodials versus slender forms, potentially reflecting geographic variation or sexual dimorphism. Camelops kansanus is considered a nomen dubium due to its indeterminate type specimen. Older generic names like Megatylopus and Procamelus refer to distinct or ancestral camelids outside the core Camelops species but have occasionally been conflated in early classifications. Placement of Camelops within the tribe Camelini of subfamily Camelinae underscores its close relation to modern Old World camels.

Evolution and phylogeny

Origins and fossil history

Camelops, classified within the subfamily Camelinae, traces its origins to the late Miocene in North America, where the lineage diverged approximately 17 to 7 million years ago from ancestors shared with protocamelids such as Paracamelus, which were part of the broader camelid radiation that began in the Eocene.[4][2] This divergence occurred amid the diversification of early camelids in North American ecosystems, with ancestral forms adapting to open habitats during a period of climatic cooling and aridification.[6] The earliest definitive fossil records of Camelops appear in the middle Pliocene, around 4.0 to 3.2 million years ago, in southern North America, marking the transition from protocamelid precursors to more derived forms.[4] Notable among these early sites are the Hagerman Fossil Beds in Idaho, which yield Blancan-age (late Pliocene to early Pleistocene) specimens representing transitional morphologies between Miocene camelids and later Camelops variants.[7] During the Pliocene, Camelops diversified across western and southern North America, with evidence of northward expansion and adaptations to varied grasslands before the onset of the Great American Biotic Interchange around 3 million years ago, during which related camelids dispersed southward.[2][6] Fossil occurrences span the Blancan land mammal age (approximately 4.75 to 1.8 million years ago) through the Irvingtonian (1.8 to 0.25 million years ago) and Rancholabrean (0.25 million to 13,000 years ago), with the genus persisting until the end of the Pleistocene.[4][3]

Phylogenetic relationships

Camelops occupies a pivotal position in the phylogeny of the Camelidae family, specifically within the tribe Camelini, as determined by molecular evidence that contrasts with earlier morphological interpretations. Cladistic analyses based on ancient DNA position Camelops as the sister taxon to the genus Camelus, encompassing the Old World camels (dromedaries and Bactrian camels), thereby distinguishing it from the South American lamines such as Lama and Vicugna. This placement indicates that Camelops belongs to the lineage of Old World camels (Camelini), which originated in North America before the ancestors of Camelus migrated to Eurasia during the Miocene, rather than evolving alongside the New World camelids. A landmark 2015 genomic study revolutionized understanding of Camelops phylogeny by sequencing mitochondrial and low-coverage nuclear genomes from late Pleistocene bones of C. hesternus recovered from Yukon Territory, Canada. The analysis confirmed that Camelops is sister to the genus Camelus (including Bactrian camels and dromedaries), nesting it firmly within Camelini and rendering prior assignments to Lamini obsolete. This evidence supports a divergence between Camelini and Lamini around 17 million years ago, with Camelops representing a basal member of the former tribe that persisted in North America until the end of the Pleistocene. Fossil-based phylogenies, relying on skeletal morphology, have historically debated Camelops' affinities, with some studies emphasizing shared traits like the robust thoracic vertebrae suggestive of humped structures—reminiscent of modern Camelus—to argue for a basal Camelini position. However, other morphological cladograms placed it within Lamini due to cranial and postcranial similarities with llamas, such as elongated metapodials. The genomic data has largely resolved these discrepancies, affirming Camelops as a distinct side branch rather than a direct ancestor to modern camels. Subsequent proteomic studies on collagen from Camelops fossils have further corroborated this placement within Camelini, aligning with genomic evidence over morphological interpretations.[8]

Physical characteristics

Size and morphology

Camelops hesternus, the most well-known species in the genus, was a large-bodied camelid with an estimated shoulder height of 2.2 meters and body weight reaching up to 800 kilograms in adults.[9] Overall body length for adults is estimated at approximately 3 meters, reflecting its robust yet elongated frame adapted for open terrain.[10] These dimensions position C. hesternus as roughly 20% larger than modern camels, emphasizing its status as one of the larger Pleistocene camelids.[9] The build of Camelops featured long, stocky limbs suited for cursorial locomotion, with elongated metapodials—metacarpals measuring 374–380 mm and metatarsals 357–388 mm—facilitating an extended stride and pacing gait.[11] The postcranial skeleton included a two-toed foot structure, with splayed toes providing stability and support, similar to extant camels; proximal phalanges bore a distinctive raised suspensory ligament scar extending nearly to the shaft center.[9][11] The skull was robust, with a long and slender rostrum, strongly arched nasals, and a deep maxillary fossa, complemented by high-crowned (hypsodont) molars designed for grinding abrasive vegetation; the dental formula was I 1/3, C 1/1, P 2/1, M 3/3, with reduced external styles on the molars and absence of lower third premolars.[9][11] Sexual dimorphism in Camelops manifested in skeletal proportions, with males exhibiting larger overall size, including thicker skulls, greater lower jaw dimensions, and more robust and longer limb bones compared to females.[9][12] Such differences are evident in fossil assemblages, where variation in bone robustness has been attributed to sex rather than distinct species in some cases.[12]

Skeletal and soft tissue features

The endocranial cast of Camelops hesternus reveals a brain volume of approximately 990 ml, significantly larger than that of modern camels such as Camelus dromedarius (570–760 ml) and South American camelids (192–276 ml).[13] This size corresponds to an estimated body mass of around 826 kg and an encephalization quotient of 0.94, indicating a moderately complex brain relative to body size.[13] The olfactory bulbs are elongated, pedunculated, and ovoid-shaped, with a narrow ethmoidal chamber featuring a dense cribriform plate, suggesting enhanced olfactory capabilities similar to those in extant Camelus species.[13] Neocortical features, including the first documented transverse coronal sulcus and ascending anterior ectosylvian sulcus in late Pleistocene camelids, point to increased neural complexity in C. hesternus compared to earlier forms.[13] Limb bones of Camelops hesternus, particularly the phalanges, are notably stocky, with unique ligament scars on the terminal phalanges distinguishing them from other camelids.[9] Fossil phalanges indicate broad, splayed toes supporting a padded foot structure adapted for traversing soft sand and rough terrain, akin to modern camelid feet that distribute weight effectively on unstable substrates.[14] Soft tissue inferences for Camelops remain speculative due to poor preservation, but the vertebral column shows no definitive modifications for supporting dorsal humps used in fat storage, unlike some related extinct camelids with elongated neural spines.[2] The presence of humps, if any, would align with adaptations in modern camels for energy reserves during scarcity, though direct evidence is absent in C. hesternus fossils.[15] Fossils of Camelops hesternus from Pleistocene deposits exhibit pathologies indicative of age-related wear and injury. Osteoarthritis is evident in the toe bones of elderly individuals, characterized by joint degeneration and bone remodeling, as seen in Rancholabrean specimens from New Mexico fissure deposits.[16] Such conditions likely arose from prolonged locomotor stress on robust limbs, though they are absent in some populations, such as those from Natural Trap Cave, Wyoming.[17] Tar pit assemblages, including those from Rancho La Brea, preserve numerous Camelops elements with potential signs of trauma from entrapment struggles, though specific injury analyses are limited.[18]

Paleobiology

Habitat and distribution

Camelops inhabited a broad geographic range across western and central North America during the Pleistocene epoch, extending from the unglaciated regions of Alaska and Yukon in the north to northern Mexico in the south.[2] Fossils indicate presence in diverse regions including the Great Plains, the southwestern deserts, and coastal areas of California and Oregon.[4] This distribution reflects the genus's adaptability to varied open terrains, supported by longer limbs suited for traversing expansive landscapes.[3] The preferred habitats of Camelops consisted primarily of open grasslands, savannas, and arid zones, where the animal likely grazed in herds amid steppe-like environments.[19] These settings were prevalent during the Pleistocene, with fossil evidence from sites in the Mojave Desert and southeastern New Mexico underscoring occupation of both dry uplands and occasionally lush wetland margins.[20] In northern latitudes, such as eastern Beringia, remains suggest habitation in tundra-steppe ecosystems during warmer intervals.[21] The distribution of Camelops exhibited temporal shifts tied to climatic fluctuations, with range expansion into higher latitudes during interglacial periods and likely contraction southward during colder glacial maxima.[22] Radiocarbon dating of 43 Camelops hesternus fossils from Alaska and Yukon, reported in 2017, confirms presence in these northern areas as early as the early Wisconsinan interstadial, supporting models of northward migration during relatively warm phases.[22] Recent discoveries have further refined understanding of this range. A 2025 reanalysis and dating of a Camelops hesternus tibia from eastern Utah, near the Green River, yielded an age of approximately 33,000 years, extending the known eastern distribution in older Pleistocene strata prior to the Last Glacial Maximum.[23]

Diet, behavior, and ecology

Camelops was a herbivorous mammal that exhibited a mixed feeding strategy as both a browser and grazer, consuming a variety of vegetation including C₃ plants such as shrubs and trees, as well as C₄ grasses and drought-tolerant shrubs like saltbush.[24] Tooth wear patterns, including microwear and mesowear analyses, further support this opportunistic diet, with evidence of low-abrasion browsing on dicots and gymnosperms alongside occasional grazing on harder, gritty vegetation.[25] Stable carbon isotope (δ¹³C) values from tooth enamel, ranging from -12.0‰ to 1.0‰ across North American sites, indicate predominant reliance on C₃ resources but with significant incorporation of C₄ plants, particularly in arid southwestern environments.[26] Stable nitrogen isotope (δ¹⁵N) data from bone collagen, combined with δ¹³C, reveal dietary shifts toward more C₄ consumption during periods of increased aridity and climatic drying in the late Pleistocene, reflecting adaptations to changing vegetation availability.[26] Fossil evidence suggests Camelops lived in small herds, similar to extant camelids, which likely facilitated predator avoidance through group vigilance and coordinated defense.[2] Bone assemblages from sites like Tule Springs Fossil Beds National Monument show clustered remains consistent with social grouping in wetland-adjacent habitats.[2] Age profiles of individuals at Rancho La Brea, derived from tooth eruption and wear sequences, indicate annual cohorts of juveniles, implying seasonal aggregation and potential herd dynamics for protection during vulnerable life stages.[27] Migratory behavior is inferred from serial sampling of tooth enamel isotopes, which document intra-tooth variations in δ¹³C and δ¹⁸O values, suggesting seasonal movements to track vegetation resources across open landscapes.[27] As a large-bodied herbivore, Camelops played a key role in Pleistocene ecosystems by shaping grassland and shrubland dynamics through selective foraging and trampling, which promoted nutrient cycling and habitat heterogeneity.[24] It served as primary prey for apex predators, including packs of dire wolves (Canis dirus) and saber-toothed cats (Smilodon fatalis), as evidenced by co-occurrence in fossil localities like Tule Springs, where predator remains align with Camelops abundance in open sagebrush deserts. These interactions highlight Camelops' position in complex food webs, where its population influenced carnivore distributions and competition among herbivores.

Extinction

Timeline and causes

The extinction of Camelops hesternus occurred during the terminal Pleistocene, with the youngest reliable radiocarbon dates placing the last occurrences around 11,000 to 10,000 years ago in mid-continental and southern North America, coinciding with the onset of the Younger Dryas cooling event (approximately 12,900 to 11,700 years ago).[28][29] A comprehensive 2017 study analyzing 43 radiocarbon dates from 34 fossils in eastern Beringia (Alaska and Yukon) revealed no evidence of late survival in far northern regions, instead confirming extirpation there during the early Wisconsinan glaciation around 75,000 years ago due to erroneous prior dates from contamination. Primary environmental drivers included rapid climate shifts during the Younger Dryas, which brought cooler, drier conditions across much of North America, leading to habitat fragmentation, reduced vegetation cover, and diminished forage availability for browsing and grazing megafauna like Camelops.[29] This period marked a broader megafaunal turnover, with aridity exacerbating resource scarcity and contributing to population declines as grasslands and woodlands contracted in favor of less productive ecosystems.[30] The overkill hypothesis posits that human hunting played a role, supported by limited archaeological evidence such as butchered remains at sites like Wally's Beach in southwestern Canada (dated ~13,000 years ago), indicating targeted exploitation by Paleoindian groups.[31][32] However, such evidence is sparse compared to other megafauna, suggesting overhunting was at most a contributing factor rather than the sole cause.[31] Regional variations highlight asynchronous extinction patterns: Camelops persisted longer in temperate southern and southwestern areas, where dated fossils indicate survival into the late Pleistocene, while northern populations in eastern Beringia vanished much earlier amid glacial advances and cold, arid interglacial conditions that eliminated suitable browse.[32]

Human interactions

Archaeological evidence indicates that prehistoric humans encountered Camelops during the late Pleistocene, particularly during the Clovis period, with direct signs of interaction at several sites. At Wally’s Beach in southern Alberta, Canada, a Clovis-era locality dated to approximately 13,300 calendar years before present (cal yr BP), excavators uncovered remains of Camelops hesternus showing multiple cut marks from stone tools on a cervical vertebra and ribs, alongside spiral fractures consistent with butchering; associated lithic artifacts and protein residues on Clovis projectile points confirm human hunting of camels and horses.[33] Similarly, at the Lubbock Lake site in Texas, dated to about 11,100 radiocarbon years BP (rcy BP), taphonomic analysis reveals cut marks and patterned breakage on Camelops bones, indicating human processing alongside horse remains.[33] Another example is the Fossil Lake site in Oregon, a probable camelid kill locality with Camelops bones exhibiting cut marks suggestive of Paleo-Indian procurement during the late Pleistocene. Hunting methods employed by these early humans targeted Camelops as part of big-game strategies, using Clovis-style spear points hafted to atlatls for thrusting or throwing. At Wally’s Beach, residues of horse and camel proteins on Clovis points demonstrate their use in hunting these species, though no embedded points have been reported in Camelops fossils; this aligns with broader evidence of Clovis hunters pursuing large herbivores through communal drives or ambushes.[33] Such techniques likely exploited Camelops' gregarious behavior in open habitats, facilitating multiple kills per event as seen in associated horse remains at the same site.[33] Cultural significance of Camelops appears limited, primarily to subsistence use for meat, hides, and possibly bone tools, with no archaeological evidence of domestication or sustained herding attempts. Bone elements from sites like Lubbock Lake show modification for marrow extraction or tool production, but post-Pleistocene Native American oral traditions rarely reference Camelops explicitly, reflecting its extinction before widespread cultural documentation.[33] The role of human interactions in Camelops' extinction remains debated, with the overkill hypothesis positing that Clovis hunting pressure contributed significantly to the decline of North American megafauna, including Camelops, around 11,000–10,500 cal yr BP.[34] Proponents argue that dated kill sites, such as those at 11,100 rcy BP, coincide with the arrival and spread of humans, potentially driving local extirpations through targeted hunting.[33] Critics, however, emphasize synergy between human predation and climatic shifts at the end of the Pleistocene, suggesting overkill alone insufficiently explains the rapid, continent-wide disappearance, as megafauna survived prior interglacials without humans.[34] This interplay is supported by the timing of the last dated Camelops remains overlapping early human expansion.[33]

Discovery and research

Historical discoveries

The genus Camelops was first described in 1854 by American paleontologist Joseph Leidy, based on a partial upper jawbone (maxilla) recovered from a gravel deposit in Kansas, which he named Camelops kansanus after the locality.[12] This initial find represented one of the earliest recognitions of extinct North American camel relatives, highlighting their distinction from modern Asian and African species despite superficial similarities in dental structure. Leidy's description emphasized the fossil's robust build and hypsodont teeth, suggesting adaptation to a grassland environment.[2] During the late 19th century, additional Camelops fossils emerged from excavations in regions like Nebraska's Niobrara River valley and California's coastal areas, where ranchers and early surveyors collected scattered bones from Pleistocene deposits. These finds, often fragmentary limb elements and vertebrae, expanded the known range of the genus across the Great Plains and Southwest, with specimens from Nebraska's Pleistocene deposits contributing to understandings of its late Pleistocene distribution. In California, preliminary recoveries near asphalt seeps foreshadowed larger discoveries, though systematic work awaited the 20th century.[35] A pivotal site for Camelops was the Rancho La Brea tar pits in Los Angeles, where over 40 individuals—primarily C. hesternus—have been unearthed since excavations began in 1906 under the direction of the University of California. These tar-trapped remains, including nearly complete skeletons, were first systematically described in the 1910s by paleontologists like John C. Merriam, revealing the species' tall stature and lack of humps, and providing the richest assemblage of Camelops fossils anywhere. Early interpretations linked Camelops closely to Asian camels, positing migration across the Bering land bridge during the Pliocene, a view later revised in the mid-20th century to emphasize its North American origins and divergence from Old World lineages.[15] Major collectors in the early 1900s, including Barnum Brown of the American Museum of Natural History, advanced Camelops research through field expeditions in Arizona and Texas, recovering skulls and postcranial elements from fissure fills and river gravels that informed initial taxonomic revisions. Brown's 1910s work at sites like the Conard Fissure in Arkansas yielded associated fauna, underscoring Camelops' role in late Pleistocene ecosystems, while collaborations with institutions like the Smithsonian further documented its morphological variation.[36]

Modern studies and analyses

In the mid-2010s, paleogenomic analyses advanced the understanding of Camelops phylogeny through ancient DNA extraction from late Pleistocene fossils. A 2015 study sequenced mitochondrial and low-coverage nuclear genomes from bones of Camelops cf. hesternus recovered from Hunker Creek in Yukon, Canada, revealing that Camelops forms a sister group to the Old World camels (genus Camelus) rather than the South American lamines, with divergence estimated in the Middle to Late Miocene around 11–10 million years ago.[4] These findings contradicted prior morphology-based classifications and highlighted the challenges of working with highly degraded ancient DNA, where sequences were limited to modal lengths of about 35 base pairs and endogenous content ranged from 13–45%, compounded by post-mortem damage like cytosine deamination.[37] Subsequent radiocarbon dating efforts refined the temporal and geographic extent of Camelops populations. A 2017 analysis of 43 new radiocarbon dates from 34 fossils across Alaska and Yukon demonstrated that western camels (C. hesternus) persisted in eastern Beringia until at least the early Wisconsinan interstadial (around 40,000–30,000 years ago), but were extirpated earlier than previously thought due to climatic cooling, thereby extending the known northern range while underscoring regional variability in survival.[22] Complementing this, a 2023 study utilized endocranial casts from Camelops hesternus crania to examine brain evolution, showing increased neocortical complexity and gyrification compared to earlier Miocene camelids, indicative of enhanced cognitive adaptations by the Pleistocene.[38] Osteological examinations have further clarified morphological consistency across Camelops specimens. In 2016, detailed assessments of postcranial fossils from Alaska and Yukon confirmed their attribution to C. hesternus, noting close similarities in limb proportions and vertebral features to southern populations like those from Rancho La Brea, despite periglacial preservation effects.[3] More recently, a 2024 discovery in Utah yielded a tibia of C. hesternus from the Green River area, dated via radiocarbon to approximately 33,000 years old and contextualized through biostratigraphy with associated Rancholabrean fauna, representing one of the geologically oldest records for the species in the region and suggesting broader Ice Age distribution in intermontane basins.[39] Interdisciplinary techniques have illuminated paleobiological aspects of Camelops. Stable carbon and oxygen isotope analyses of tooth enamel from Pleistocene sites indicate a mixed diet dominated by C3 browse but incorporating up to 40–50% C4 grasses in arid environments, reflecting opportunistic foraging adapted to open woodlands and grasslands.[40]

References

  1. Genomic Data from Extinct North American Camelops Revise Camel ...
  2. The Camels (U.S. National Park Service)
  3. Osteological Assessment of Pleistocene Camelops hesternus ...
  4. Genomic Data from Extinct North American Camelops Revise Camel ...
  5. Camelops: North American Ancestor of All Camels - Historic Mysteries
  6. [PDF] Giant Camels from the Cenozoic of North America
  7. A review of Camelops (Mammalia, Artiodactyla, Camelidae), a giant ...
  8. Trends in the paleodietary habits of fossil camels from the Tertiary ...
  9. [PDF] Genomic data from extinct North American Camelops revises camel ...
  10. (PDF) A review of Camelops (Mammalia, Artiodactyla, Camelidae), a ...
  11. LibGuides: Extinct Western Camel (Camelops hesternus) Fact Sheet ...
  12. Camelops hesternus (Pleistocene western camel)
  13. Endocranial Casts of Camelops hesternus and Palaeolama sp. - NIH
  14. The Nat | Camel - San Diego Natural History Museum
  15. L.A.'s Ancient Camel | La Brea Tar Pits
  16. [PDF] Late Pleistocene (Rancholabrean) mammals from fissure deposits in ...
  17. Diseases & Pathology - Extinct Western Camel (Camelops ...
  18. Our Research | La Brea Tar Pits
  19. Distribution & Habitat - Extinct Western Camel (Camelops hesternus ...
  20. [PDF] The Camels - BirdAndHike.com
  21. Last interglacial western camel (Camelops hesternus) from eastern ...
  22. A case of early Wisconsinan “over-chill”: New radiocarbon evidence ...
  23. Ice Age Camel Fossil Found Along the Green River in Utah
  24. https://doi.org/10.1016/j.palaeo.2016.08.036
  25. https://doi.org/10.1016/j.palaeo.2021.110360
  26. [PDF] diet and water source of pleistocene lamini camelids based on
  27. ASSESSING MIGRATION IN PLEISTOCENE HERBIVORES AT ...
  28. Camel fossils from gravel pits near Edmonton and Vauxhall, and a ...
  29. Rapid range shifts and megafaunal extinctions associated with late ...
  30. Climate‐driven ecological stability as a globally shared cause of ...
  31. Late Pleistocene Western Camel (Camelops Hesternus) Hunting in ...
  32. Late Pleistocene horse and camel hunting at the southern margin of ...
  33. Late Pleistocene horse and camel hunting at the southern ... - PNAS
  34. Paleo-Indian procurement of Camelops on the northwestern plains
  35. https://www.smu.edu/-/media/site/dedman/departments/anthropology/pdf/meltzer/meltzer-2015-ann-rev-anth-pleistocene-overkill-and-north-american-mammalian-extinctions.ashx
  36. Jefferson : Nebraska County Fossils : Science & Culture - Morrill Hall
  37. [PDF] Proceedings of the United States National Museum
  38. Genomic Data from Extinct North American Camelops Revise Camel ...
  39. Dietary ecology of Pleistocene camelids: Influences of climate ...
  40. (PDF) Osteological Assessment of Pleistocene Camelops hesternus ...
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