Panthera balamoides

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Panthera balamoides
Temporal range: Late Pleistocene (Rancholabrean)
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Panthera balamoides holotype.jpg
Holotype humerus in anterior and posterior views.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Suborder: Feliformia
Family: Felidae
Subfamily: Pantherinae
Genus: Panthera
Species:
†P. balamoides
Binomial name
†Panthera balamoides
Stinnesbeck et al., 2019

Panthera balamoides ("similar to jaguar") is a species described as an extinct species of the big cat genus Panthera that is known from a single fossil found in a Late Pleistocene (Rancholabrean NALMA, dated to 13,000 BP) age cenote in the Yucatan Peninsula, Mexico. P. balamoides has only a single reported specimen, the distal end of a right humerus (upper arm bone), that is notably of exceptional size for a felid. It was unearthed in 2012 from an underwater cave and described in 2019 by an international group of paleontologists from Mexico and Germany led by Sarah R. Stinnesbeck. However, several authors have since proposed that the fossil comes from an ursid, possibly the extinct Arctotherium , and not of felid affinities.

Contents

P. balamoides lived at the end of the Pleistocene, going extinct during the Quaternary Extinction Event with other megafauna. It has been inferred that it was cursorial in habits, with good climbing abilities like modern jaguars. This created a niche partition between it and other felids like the saber-toothed Smilodon which hunted in open environments.

Discovery

Fossils attributed to Panthera balamoides were first unearthed from a debris mount in El Pit cenote, a submerged sinkhole in a diving and snorkel park known as Dos Ojos on the Yucatán Peninsula. [1] This site is located near Tulum in Quintana Roo, Mexico, dating to the Rancholabrean stage of the Late Pleistocene of around 13,000 BP, [2] [3] [1] in which several other fossils were unearthed such as two human individuals and other felids like Smilodon and Panthera atrox. The fossils had been discovered and collected in 2012 via diving by Jerónimo Avilés Olguín, a paleontologist from the Museo del Desierto, from around 44 meters down in the cenote. The fossils later attributed to P. balamoides are fragmentary, consisting only of the distal end of a humerus (upper arm bone) that was later taken and dried in the Colección Paleontológica de Coahuila of the Museo del Desierto in Saltillo, Mexico. [1]

The specimen, desposited under specimen number CPC-2205, remained undescribed until 2018. That year, a team of researchers from Germany and Mexico led by Sarah R. Stinnesbeck described the remains in addition to clavicles from Panthera atrox and a distal humerus of Smilodon gracilis. [4] [1] CPC-2205 was made the holotype of a novel species named Panthera balamoides, the specific name coming from "balam", the Mayan word for "jaguar" due to the discovery of the remains in former Mayan territory, and "eidos" from the Greek root for "similarity". The name calls upon the supposed likeness of the distal humerus' morphology to that of the extant jaguar. [4] [1]

Map of Mexico, with Quintana Roo highlighted in green. Mexico states quintana-roo.png
Map of Mexico, with Quintana Roo highlighted in green.

Description

Depending on the phylogenetic position of the species, it have either been a very large and robust pantherine similar to jaguars or a ginormous omnivorous ursid like Arctotherium. If P. balamoides is a Panthera species, it may have been over 100 kilograms (220 lb) in weight despite its build more akin to smaller felids such as jaguars and ocelots. [1] This would make P. balamoides one of the largest known carnivorans, around the weight of modern Asiatic bears and jaguars. [5] [6] If a specimen of Arctotherium, it would be from the smaller species A. wingei based on the discovery of nearby remains. A. wingei has been estimated to have been closer to 83 kilograms (183 lb). [7] [8] [9]

Humerus

Portrait of the bear Arctotherium, which P. balamoides may be a synonym of. Arctotherium.jpg
Portrait of the bear Arctotherium , which P. balamoides may be a synonym of.

The holotype consists purely of the distal third of the right humerus (upper arm bone), with a preserved length of 136 millimetres (5.4 in) and maximum width of 81 millimetres (3.2 in). The humeral shaft is gracile and straight, attached to a prominent lateral supracondylar ridge with a distal thickness and a laterally convex ridge runs along the distal half of the shaft. Here, the m. bracialis muscle would contact the bone next to the m. triceps brachii. There is a crescent-shaped concave depression proximal to the articlar surfaces that would be a muscle attachment. There is an offset distal articular surface (joint) that longs along the axis of the humeral shaft medially. The epticondylar foramen is prominent and visible from the front and backsides, a trait used by the authors to diagnose the fossil. The coronoid fossa (a small depression) is shallow and located on the anterior face of the epiphysis (end of a long bone) adjacent to the distal articular surface, with an abraded capitulum and trochlea, the parts of the humerus that articulate with the ulna and radius. [1]

The olecranon fossa (depression that articulates with the radius) is located proximal to the distal articlular surface, with a height and weight of around 30 millimetres (1.2 in) making a triangular shape. This fossa was under the attachment of the m. anconeus muscle, making a firm and robust accessory point. [1] These traits of the humerus suggests P. balamoides had robust and short, akin to that of extant jaguars. A combination of these characteristics were used to diagnose the species by Stinnesbeck et al. (2019), but have come into question by other authors who theorize the humerus is not distinct from that of Arctotherium. [9]

Classification

In the initial description of P. balamoides, it was decided by the authors that the partial humerus of the holotype could not have been canid or ursid due to the presence of an entepicondylar foramen, which is absent in the two groups with the exception of tremarctine bears like Tremarctos. Other traits like the size and outline of the foramen as well as the distribution of Tremarctos led the authors to favor a placement in Felidae. [1] The humerus preserves a combination of pantherine and machairodontine features, such as the entepicondylar foramen's shape though it is over twice as large as that of Smilodon's. This foramen is missing from humeri of Smilodon populator, [10] [11] leading the authors to speculate that P. balamoides was a pantherine. This, in addition to characteristics like the olecranon fossa's outline and size of the supracondylar process, convinced Stinnesbeck et al. (2019) to put the species in Panthera. They did note, however, that additional material was required to make a solid phylogenetic assessment. [1]

However, a 2019 study on Yucatán carnivorans suggested that Panthera balamoides may actually be misidentified remains of Arctotherium (a tremarctine bear), whose remains have also been found in Yucatán. If so, this would explain the unusual robustness of the bone and render Panthera balamoides an invalid species. [9] [12] The idea of a felid Panthera balamoides has not been repeated in literature, with a study on Mexican jaguar fossils also considering P. balamoides to be an ursid based on morphological characteristics and mentioned by several other works. [13] [14] A 2023 study also agreed that P. balamoides has nothing in common with Panthera, and that it is morphologically similar to Arctotherium. [15]

Paleoecology

Based on the thickness of the cortical bone in the humerus, it was hypothesized by Stinnesbeck et al. that P. balamoides had powerful forelimbs akin to Smilodon that could be used for wrestling its prey. [1] [16] This has been theorized to have reduced the range of humeral abduction and greatened the amount of lateral rotation, indicating an arboreal (climbing) lifestyle. [17] [1] The greater ability of movement in the forelimbs made activities like short-distance running, jumping, climbing, and wrestling possible, an unusual trait for such a large animal. [1] This is in contrast to other pantherines, which bear a thicker cortical bone for a more pursuit-predator lifestyle. [1] [16] The olecranon fossa is short and shallow, suggesting a larger degree of elbow and arm extension was capable, a trait beneficial to arboreal animals. Several other characteristics of the humerus support the idea of arboreal or scansorial habits, features that led Stinnesbeck et al. to suggest that P. balamoides was an accelerator and competent jumper with the ability to climb tall rocks. This is more similar to smaller felines like jaguars, ocelots, and jaguarundis instead of larger pantherines. The arboreal habits may have led P. balamoides to occupy more dense habitats rather than the open habitats which featured cursorial felids like Homotherium, Panthera atrox, and Smilodon. [1] [18] [19] [16]

P. balamoides is known from a single site in the Yucatán dating to the Rancholabrean NALMA (North American Land Mammal Age) from around 13,000 BP, this being at the end of the Pleistocene and reign of many megafauna groups in the Americas. [1] [9] The areas around El Pit cenote likely had large open steppes separating the more densely forested shrubs on the Yucatán savannahs, explaining why a mix of cursorial and arboreal animal fossils have been collected from the locality. [1] The El Pit cenote is one of several cenotes known from the Pleistocene Yucatán, with the Hoyo Negro system that is also submerged being very fossil productive. [14] [9] [4] [2] This includes fossils of humans, [20] the gomphothere proboscidean Cuvieronius, ground sloths Nohochichak [21] and two species of Xibalbaonyx , [4] [22] large canid Protocyon , other fossil felids Panthera atrox and Smilodon in addition to the extant Puma and Lynx , [9] [13] procyonid Nasua , tayassuid Pecari , tapir Tapirus bairdii , and the giant ursid Arctotherium. [8] [23] It was postulated by Stinnesbeck et al. (2019) that P. balamoides used the caves for water as the densely forested environments it inhabited were devoid of drinking spots. [1]

Related Research Articles

Panthera is a genus within the family Felidae that was named and described by Lorenz Oken in 1816 who placed all the spotted cats in this group. Reginald Innes Pocock revised the classification of this genus in 1916 as comprising the tiger, lion, jaguar, and leopard on the basis of common features of their skulls. Results of genetic analysis indicate that the snow leopard also belongs to the genus Panthera, a classification that was accepted by IUCN Red List assessors in 2008.

<i>Smilodon</i> Extinct genus of saber-toothed cat

Smilodon is a genus of felids belonging to the extinct subfamily Machairodontinae. It is one of the best known saber-toothed predators and prehistoric mammals. Although commonly known as the saber-toothed tiger, it was not closely related to the tiger or other modern cats. Smilodon lived in the Americas during the Pleistocene epoch. The genus was named in 1842 based on fossils from Brazil; the generic name means "scalpel" or "two-edged knife" combined with "tooth". Three species are recognized today: S. gracilis, S. fatalis, and S. populator. The two latter species were probably descended from S. gracilis, which itself probably evolved from Megantereon. The hundreds of specimens obtained from the La Brea Tar Pits in Los Angeles constitute the largest collection of Smilodon fossils.

<span class="mw-page-title-main">Tulum</span> Maya site in Quintana Roo, Mexico

Tulum is the site of a pre-Columbian Mayan walled city which served as a major port for Coba, in the Mexican state of Quintana Roo. The ruins are situated on 12-meter-tall (39 ft) cliffs along the east coast of the Yucatán Peninsula on the Caribbean Sea. Tulum was one of the last cities built and inhabited by the Maya and achieved its greatest prominence between the 13th and 15th centuries. Maya continued to occupy Tulum for about 70 years after the Spanish began occupying Mexico, but the city was abandoned by the end of the 16th century. Tulum is one of the best-preserved coastal Maya sites, and today a popular site for tourists.

<span class="mw-page-title-main">American lion</span> Extinct species of carnivore

Panthera atrox, better known as the American lion, also called the North American lion, or American cave lion, is an extinct pantherine cat. Panthera atrox lived in North America during the Pleistocene epoch, from around 340,000 to 12,800 years ago. The species was initially described by American paleontologist Joseph Leidy in 1853 based on a fragmentary mandible (jawbone) from Mississippi; the species name ('atrox') means "savage" or "cruel". The status of the species is debated, with some mammalogists and paleontologists considering it a distinct species or a subspecies of Panthera leo, which contains living lions. However, novel genetic evidence has shown that it is instead a distinct species derived from the Eurasian cave or steppe lion, evolving after its geographic isolation in North America. Its fossils have been excavated from Alaska to Mexico. It was about 25% larger than the modern lion, making it one of the largest known felids.

<span class="mw-page-title-main">Yucatán Peninsula</span> Peninsula in North America

The Yucatán Peninsula is a large peninsula in southeast Mexico and adjacent portions of Belize and Guatemala. The peninsula extends towards the northeast, separating the Gulf of Mexico to the north and west of the peninsula from the Caribbean Sea to the east. The Yucatán Channel, between the northeastern corner of the peninsula and Cuba, connects the two bodies of water.

<i>Thylacosmilus</i> Extinct genus of mammals

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<span class="mw-page-title-main">Pantherinae</span> Subfamily of felids

The Pantherinae is a subfamily of the Felidae; it was named and first described by Reginald Innes Pocock in 1917 as only including the Panthera species. The Pantherinae genetically diverged from a common ancestor between 9.32 to 4.47 million years ago and 10.67 to 3.76 million years ago.

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<span class="mw-page-title-main">Tremarctinae</span> Subfamily of bears

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<i>Arctotherium</i> Extinct genus of bears

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References

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  19. ↑ Christiansen, Per; Harris, John M. (2009-09-12). "Craniomandibular morphology and phylogenetic affinities of Panthera atrox : implications for the evolution and paleobiology of the lion lineage". Journal of Vertebrate Paleontology. 29 (3): 934–945. Bibcode:2009JVPal..29..934C. doi:10.1671/039.029.0314. ISSN   0272-4634. S2CID   85975640.
  20. ↑ Stinnesbeck, Wolfgang; Becker, Julia; Hering, Fabio; Frey, Eberhard; González, Arturo González; Fohlmeister, Jens; Stinnesbeck, Sarah; Frank, Norbert; Mata, Alejandro Terrazas; Benavente, Martha Elena; Olguín, Jerónimo Avilés; Núñez, Eugenio Aceves; Zell, Patrick; Deininger, Michael (2017-08-30). "The earliest settlers of Mesoamerica date back to the late Pleistocene". PLOS ONE. 12 (8): e0183345. Bibcode:2017PLoSO..1283345S. doi: 10.1371/journal.pone.0183345 . ISSN   1932-6203. PMC   5576649 . PMID   28854194.
  21. ↑ McDonald, H. Gregory; Chatters, James C.; Gaudin, Timothy J. (2017-05-04). "A new genus of megalonychid ground sloth (Mammalia, Xenarthra) from the late Pleistocene of Quintana Roo, Mexico". Journal of Vertebrate Paleontology. 37 (3): e1307206. Bibcode:2017JVPal..37E7206M. doi:10.1080/02724634.2017.1307206. ISSN   0272-4634. S2CID   90414512.
  22. ↑ Stinnesbeck, Sarah R.; Frey, Eberhard; Olguín, Jerónimo Avíles; Stinnesbeck, Wolfgang; Zell, Patrick; Mallison, Heinrich; González González, Arturo; Aceves Núñez, Eugenio; Velázquez Morlet, Adriana; Terrazas Mata, Alejandro; Benavente Sanvicente, Martha; Hering, Fabio; Rojas Sandoval, Carmen (2017-06-01). "Xibalbaonyx oviceps, a new megalonychid ground sloth (Folivora, Xenarthra) from the Late Pleistocene of the Yucatán Peninsula, Mexico, and its paleobiogeographic significance". PalZ. 91 (2): 245–271. doi:10.1007/s12542-017-0349-5. ISSN   1867-6812. S2CID   134188352.
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