Post by Vodmeister on Mar 19, 2014 10:35:55 GMT 5
Pachycrocuta brevirostris
Life restoration of P. brevirostris. © @ Mauricio Antón.
Temporal range: Quaternary; Early Pleistocene to Late Pleistocene; Gelasian to Calabrian (~2 to ~0.8 Ma)[1][2]
Scientific classification:
Life
Domain: Eukaryota
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
(unranked): Bilateria
Clade: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Clade: Olfactores
Clade: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Clade: Eugnathostomata
Clade: Teleostomi
Superclass: Tetrapoda
Clade: Reptiliomorpha
Clade: Amniota
Clade: Synapsida
Clade: Eupelycosauria
Clade: Sphenacodontia
Clade: Sphenacodontoidea
Order: Therapsida
Clade: Eutheriodonta
Suborder: Cynodontia
Clade: Epicynodontia
Infraorder: Eucynodontia
Parvorder: Probainognathia
Superfamily: Chiniquodontoidea
Clade: Prozostrodontia
Clade: Mammaliaformes
Class: Mammalia
Clade: Holotheria
Superlegion: Trechnotheria
Legion: Cladotheria
Sublegion: Zatheria
Infralegion: Tribosphenida
Subclass: Theria
Clade: Eutheria
Infraclass: Placentalia
Subcohort: Exafroplacentalia
Magnorder: Boreoeutheria
Superorder: Laurasiatheria
(unranked): Ferae
(unranked): Carnivoramorpha
Order: Carnivora
Suborder: Feliformia
Family: Hyaenidae
Genus: †Pachycrocuta
Species: †P. brevirostris
Pachycrocuta is an extinct genus of hyena that lived across Eurasia from the Early to Late Pleistocene.
Evolution:
The Pachycrocuta lineage evolved from the late Miocene genus Hyaenictitherium. It first appeared in western Europe around ~1.9 million years ago.[1] A recently discovered Pachycrocuta skull from China suggests the forerunner of P. brevirostris brevirostris appeared in northeast Asia as early as ~2 million years ago, suggesting the species migrated out of northeast Asia into Europe.[2]
Description:
Pachycrocuta had an enormous skull. The basal lengths of the Sainzelles type specimen and Zhoukoudian skull are estimated at 322 mm and 315 mm, respectively. This rivals the skull lengths of southern African male lions (241-328 mm).[1] A skull from China was slightly bigger than the Sainzelles specimen.[2] This species differed from modern hyenas in that the radius and tibia were shortened relative to the humerus and femur. It’s been suggested that the shoulder height of the giant hyena (90-100 cm) was actually not much greater than that of a spotted hyena (85 cm), resulting in a shorter animal that skull size alone would suggest.[1]
Regression equations for body mass based on postcranial measurements and craniodental variables in living carnivores suggest that Pachycrocuta brevirostris weighed ~110 kg.[1]
Predation and scavenging:
It has been unclear as to whether or not Pachycrocuta was an active predator like the modern spotted hyena or more of a scavenger like the striped and brown hyenas. Pachycrocuta had more heavily built limbs and shortened distal limb segments compared to modern hyenas. Its brachial index (radius to humerus length) was 0.91 (range in modern hyenas is 1.00 to 1.08), while its crural index (tibia to femur length) was 0.74 (range in modern hyenas is 0.82-0.88). This would have made it less suited to a cursorial lifestyle, but at the same time would have provided more power and stability to dismember and carry large pieces of ungulate carcasses. The large body size and robust limbs of Pachycrocuta may also have been a useful asset when hunting medium to large-sized prey.[1]
In bone-crushing hyenas, the anterior and posterior cusps of the premolars are reduced while the central one is enlarged and widened. This turns the tooth from a flesh-slicing blade (like in felids) to a heavy conical hammer. The dimensions of the fourth (and third) premolar of P. brevirostris indicate that it was indeed able to crush large bones. The active predatory spotted hyena has a relatively elongated trigonid blade in the lower carnassial, while the scavenging brown and striped hyenas have a more robust talonid basin. The relative proportions of the lower teeth of Pachycrocuta are more like those of scavenging hyenas, with a large talonid basin in the lower carnassial and a relatively short trigonid blade, further supporting bone-cracking habits in this species. Also, the relative distance between the mandibular condyle and the first molar are similar in Pachycrocuta and the brown hyena, indicating Pachycrocuta had the ability to accommodate bones of large diameter while being able to bite hard.[1]
The moment arm of resistance (MAR) at the canines of Pachycrocuta has been compared with that of modern hyenas. Compared to the values of MAR for modern hyenas, that for Pachycrocuta is higher than expected for a hyena of its body mass. This indicates a loss of bite strength at the canines. This has been taken to mean that Pachycrocuta had less predatory abilities compared to living hyenas and felids. Also, the high value of MAR (which measures mandible length) suggests the name “short-faced” hyena is actually a misnomer. Jaw depth is consistent with bone-cracking, and the mandible is shaped similarly to those of the brown and striped hyenas, which eat more bones.[1]
Furthermore, the mandible of the spotted hyena is characterized by a well-developed carnassial, curved mandibular corpus, and a shallow mandibular body below the premolars and the canine tooth. By contrast, the jaws of the brown, spotted, and giant hyenas are straighter, deeper below the premolars and canine, and have a shorter carnassial tooth. This also highlights Pachycrocuta’s similarities with the brown and striped hyenas (which are specialized bone-cracking scavengers) in contrast with the spotted hyena (which is more of an active predator), although Pachycrocuta’s deeper mandibular corpus and more developed symphysis indicate even more extreme adaptation towards bone-cracking than in the brown and striped hyenas.[1]
A bone assemblage at Venta Micena further supports a scavenging lifestyle in Pachycrocuta. The skeletal remains found were scavenged by giant hyenas after predation by flesh-eating carnivores. Bones with greater marrow content and lower mineral density (femur, humerus, and tibia) were preferentially fractured by the hyenas, while bones with less nutritional value (metapodials and the radius) were better represented as complete elements. A pattern of proximodistal bone consumption (of humeri and tibiae) was also found. Bone accumulations made by striped hyenas are similar to those found at Venta Micena.[1]
However, it must be emphasized that no living mammalian carnivore lives entirely off of scavenging, with vultures being the only true vertebrate scavengers (due to their energetically efficient soaring capabilities). Likewise, the brown and striped hyenas have more lightly built postcranial skeletons than the spotted hyena, an adaptation to cover longer distances to search for carcasses. The shorter legs and much greater body mass of Pachycrocuta brevirostris would be disadvantageous to this lifestyle. Lastly, almost all carnivorans ~21 kg or heavier take prey as large as, if not larger than themselves. It would seem incredulous that a hyena this massive could live primarily as a scavenger, and it would be inconceivable that it could live solely off of scavenging. It is possible that Pachycrocuta did not travel long distances to search for carcasses, but instead followed other predators and exploited kills as a kleptoparasite. High carcass predictability (especially in open habitat like Venta Micena) and the presence of scavenging birds would both be prerequisites for a highly specialized scavenging lifestyle.[1]
Competition with hominins:
The Villafranchian was followed by the Epivillafranchian (~1.2-0.8 Ma), a period of climatic instability and several strong glacial periods. Despite this, it appears that the composition of large mammal assemblages, especially the large carnivore guild, did not significantly change as a result. If Pachycrocuta competed with early Homo for carcasses killed by large predators, it would have remained this way throughout the Epivillafranchian.[3]
Extinction:
Pachycrocuta brevirostris did not persist beyond ~800,000 years ago. This was the point at which it was replaced by Crocuta crocuta and “Hyaena” prisca appeared; Crocuta did not coexist with Pachycrocuta.[4]
It’s been suggested that the extinction of Pachycrocuta was probably related to the decline and extinction of contemporary saber-toothed cats. Pantherine cats arrived in Europe during the Middle Pleistocene, and they presumably consumed more from their kills than saber-toothed cats did. This would have resulted in the loss of a regular source of scavengeable carcasses for Pachycrocuta.[1]
References:
[1] Palmqvist, P., Martínez-Navarro, B., Pérez-Claros, J. A., Torregrosa, V., Figueirido, B., Jiménez-Arenas, J. M., ... & De Renzi, M. (2011). The giant hyena Pachycrocuta brevirostris: modelling the bone-cracking behavior of an extinct carnivore. Quaternary International, 243(1), 61-79.
[2] Liu, J., Liu, J., Zhang, H., Wagner, J., Jiangzuo, Q., Song, Y., ... & Jin, C. (2021). The giant short-faced hyena Pachycrocuta brevirostris (Mammalia, Carnivora, Hyaenidae) from Northeast Asia: A reinterpretation of subspecies differentiation and intercontinental dispersal. Quaternary International, 577, 29-51.
[3] Madurell-Malapeira, J., Alba, D. M., Espigares, M. P., Vinuesa, V., Palmqvist, P., Martínez-Navarro, B., & Moyà-Solà, S. (2017). Were large carnivorans and great climatic shifts limiting factors for hominin dispersals? Evidence of the activity of Pachycrocuta brevirostris during the Mid-Pleistocene Revolution in the Vallparadís Section (Vallès-Penedès Basin, Iberian Peninsula). Quaternary International, 431, 42-52.
[4] Iannucci, A., Mecozzi, B., Sardella, R., & Iurino, D. A. (2021). The extinction of the giant hyena Pachycrocuta brevirostris and a reappraisal of the Epivillafranchian and Galerian Hyaenidae in Europe: Faunal turnover during the Early–Middle Pleistocene Transition. Quaternary Science Reviews, 272, 107240.
Life restoration of P. brevirostris. © @ Mauricio Antón.
Temporal range: Quaternary; Early Pleistocene to Late Pleistocene; Gelasian to Calabrian (~2 to ~0.8 Ma)[1][2]
Scientific classification:
Life
Domain: Eukaryota
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
(unranked): Bilateria
Clade: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Clade: Olfactores
Clade: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Clade: Eugnathostomata
Clade: Teleostomi
Superclass: Tetrapoda
Clade: Reptiliomorpha
Clade: Amniota
Clade: Synapsida
Clade: Eupelycosauria
Clade: Sphenacodontia
Clade: Sphenacodontoidea
Order: Therapsida
Clade: Eutheriodonta
Suborder: Cynodontia
Clade: Epicynodontia
Infraorder: Eucynodontia
Parvorder: Probainognathia
Superfamily: Chiniquodontoidea
Clade: Prozostrodontia
Clade: Mammaliaformes
Class: Mammalia
Clade: Holotheria
Superlegion: Trechnotheria
Legion: Cladotheria
Sublegion: Zatheria
Infralegion: Tribosphenida
Subclass: Theria
Clade: Eutheria
Infraclass: Placentalia
Subcohort: Exafroplacentalia
Magnorder: Boreoeutheria
Superorder: Laurasiatheria
(unranked): Ferae
(unranked): Carnivoramorpha
Order: Carnivora
Suborder: Feliformia
Family: Hyaenidae
Genus: †Pachycrocuta
Species: †P. brevirostris
Pachycrocuta is an extinct genus of hyena that lived across Eurasia from the Early to Late Pleistocene.
Evolution:
The Pachycrocuta lineage evolved from the late Miocene genus Hyaenictitherium. It first appeared in western Europe around ~1.9 million years ago.[1] A recently discovered Pachycrocuta skull from China suggests the forerunner of P. brevirostris brevirostris appeared in northeast Asia as early as ~2 million years ago, suggesting the species migrated out of northeast Asia into Europe.[2]
Description:
Pachycrocuta had an enormous skull. The basal lengths of the Sainzelles type specimen and Zhoukoudian skull are estimated at 322 mm and 315 mm, respectively. This rivals the skull lengths of southern African male lions (241-328 mm).[1] A skull from China was slightly bigger than the Sainzelles specimen.[2] This species differed from modern hyenas in that the radius and tibia were shortened relative to the humerus and femur. It’s been suggested that the shoulder height of the giant hyena (90-100 cm) was actually not much greater than that of a spotted hyena (85 cm), resulting in a shorter animal that skull size alone would suggest.[1]
Regression equations for body mass based on postcranial measurements and craniodental variables in living carnivores suggest that Pachycrocuta brevirostris weighed ~110 kg.[1]
Predation and scavenging:
It has been unclear as to whether or not Pachycrocuta was an active predator like the modern spotted hyena or more of a scavenger like the striped and brown hyenas. Pachycrocuta had more heavily built limbs and shortened distal limb segments compared to modern hyenas. Its brachial index (radius to humerus length) was 0.91 (range in modern hyenas is 1.00 to 1.08), while its crural index (tibia to femur length) was 0.74 (range in modern hyenas is 0.82-0.88). This would have made it less suited to a cursorial lifestyle, but at the same time would have provided more power and stability to dismember and carry large pieces of ungulate carcasses. The large body size and robust limbs of Pachycrocuta may also have been a useful asset when hunting medium to large-sized prey.[1]
In bone-crushing hyenas, the anterior and posterior cusps of the premolars are reduced while the central one is enlarged and widened. This turns the tooth from a flesh-slicing blade (like in felids) to a heavy conical hammer. The dimensions of the fourth (and third) premolar of P. brevirostris indicate that it was indeed able to crush large bones. The active predatory spotted hyena has a relatively elongated trigonid blade in the lower carnassial, while the scavenging brown and striped hyenas have a more robust talonid basin. The relative proportions of the lower teeth of Pachycrocuta are more like those of scavenging hyenas, with a large talonid basin in the lower carnassial and a relatively short trigonid blade, further supporting bone-cracking habits in this species. Also, the relative distance between the mandibular condyle and the first molar are similar in Pachycrocuta and the brown hyena, indicating Pachycrocuta had the ability to accommodate bones of large diameter while being able to bite hard.[1]
The moment arm of resistance (MAR) at the canines of Pachycrocuta has been compared with that of modern hyenas. Compared to the values of MAR for modern hyenas, that for Pachycrocuta is higher than expected for a hyena of its body mass. This indicates a loss of bite strength at the canines. This has been taken to mean that Pachycrocuta had less predatory abilities compared to living hyenas and felids. Also, the high value of MAR (which measures mandible length) suggests the name “short-faced” hyena is actually a misnomer. Jaw depth is consistent with bone-cracking, and the mandible is shaped similarly to those of the brown and striped hyenas, which eat more bones.[1]
Furthermore, the mandible of the spotted hyena is characterized by a well-developed carnassial, curved mandibular corpus, and a shallow mandibular body below the premolars and the canine tooth. By contrast, the jaws of the brown, spotted, and giant hyenas are straighter, deeper below the premolars and canine, and have a shorter carnassial tooth. This also highlights Pachycrocuta’s similarities with the brown and striped hyenas (which are specialized bone-cracking scavengers) in contrast with the spotted hyena (which is more of an active predator), although Pachycrocuta’s deeper mandibular corpus and more developed symphysis indicate even more extreme adaptation towards bone-cracking than in the brown and striped hyenas.[1]
A bone assemblage at Venta Micena further supports a scavenging lifestyle in Pachycrocuta. The skeletal remains found were scavenged by giant hyenas after predation by flesh-eating carnivores. Bones with greater marrow content and lower mineral density (femur, humerus, and tibia) were preferentially fractured by the hyenas, while bones with less nutritional value (metapodials and the radius) were better represented as complete elements. A pattern of proximodistal bone consumption (of humeri and tibiae) was also found. Bone accumulations made by striped hyenas are similar to those found at Venta Micena.[1]
However, it must be emphasized that no living mammalian carnivore lives entirely off of scavenging, with vultures being the only true vertebrate scavengers (due to their energetically efficient soaring capabilities). Likewise, the brown and striped hyenas have more lightly built postcranial skeletons than the spotted hyena, an adaptation to cover longer distances to search for carcasses. The shorter legs and much greater body mass of Pachycrocuta brevirostris would be disadvantageous to this lifestyle. Lastly, almost all carnivorans ~21 kg or heavier take prey as large as, if not larger than themselves. It would seem incredulous that a hyena this massive could live primarily as a scavenger, and it would be inconceivable that it could live solely off of scavenging. It is possible that Pachycrocuta did not travel long distances to search for carcasses, but instead followed other predators and exploited kills as a kleptoparasite. High carcass predictability (especially in open habitat like Venta Micena) and the presence of scavenging birds would both be prerequisites for a highly specialized scavenging lifestyle.[1]
Competition with hominins:
The Villafranchian was followed by the Epivillafranchian (~1.2-0.8 Ma), a period of climatic instability and several strong glacial periods. Despite this, it appears that the composition of large mammal assemblages, especially the large carnivore guild, did not significantly change as a result. If Pachycrocuta competed with early Homo for carcasses killed by large predators, it would have remained this way throughout the Epivillafranchian.[3]
Extinction:
Pachycrocuta brevirostris did not persist beyond ~800,000 years ago. This was the point at which it was replaced by Crocuta crocuta and “Hyaena” prisca appeared; Crocuta did not coexist with Pachycrocuta.[4]
It’s been suggested that the extinction of Pachycrocuta was probably related to the decline and extinction of contemporary saber-toothed cats. Pantherine cats arrived in Europe during the Middle Pleistocene, and they presumably consumed more from their kills than saber-toothed cats did. This would have resulted in the loss of a regular source of scavengeable carcasses for Pachycrocuta.[1]
References:
[1] Palmqvist, P., Martínez-Navarro, B., Pérez-Claros, J. A., Torregrosa, V., Figueirido, B., Jiménez-Arenas, J. M., ... & De Renzi, M. (2011). The giant hyena Pachycrocuta brevirostris: modelling the bone-cracking behavior of an extinct carnivore. Quaternary International, 243(1), 61-79.
[2] Liu, J., Liu, J., Zhang, H., Wagner, J., Jiangzuo, Q., Song, Y., ... & Jin, C. (2021). The giant short-faced hyena Pachycrocuta brevirostris (Mammalia, Carnivora, Hyaenidae) from Northeast Asia: A reinterpretation of subspecies differentiation and intercontinental dispersal. Quaternary International, 577, 29-51.
[3] Madurell-Malapeira, J., Alba, D. M., Espigares, M. P., Vinuesa, V., Palmqvist, P., Martínez-Navarro, B., & Moyà-Solà, S. (2017). Were large carnivorans and great climatic shifts limiting factors for hominin dispersals? Evidence of the activity of Pachycrocuta brevirostris during the Mid-Pleistocene Revolution in the Vallparadís Section (Vallès-Penedès Basin, Iberian Peninsula). Quaternary International, 431, 42-52.
[4] Iannucci, A., Mecozzi, B., Sardella, R., & Iurino, D. A. (2021). The extinction of the giant hyena Pachycrocuta brevirostris and a reappraisal of the Epivillafranchian and Galerian Hyaenidae in Europe: Faunal turnover during the Early–Middle Pleistocene Transition. Quaternary Science Reviews, 272, 107240.
