Post by Infinity Blade on Jun 27, 2023 19:05:27 GMT 5
Sardinian dhole – Cynotherium spp.
Life reconstruction of Cynotherium sardous hunting the Sardinian pika (Prolagus sardus). © @ Peter Schouten (click here-> to view the larger image this is a part of).
Temporal range: Quaternary; Late Calabrian to Upper Pleistocene (>800-13.5 kya[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
(unranked): Pegasoferae
(unranked): Zooamata
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: Caniformia
Clade: Canoidea
Infraorder: Cynoidea
Family: Canidae
Subfamily: Canine
Tribe: Canini
Genus: †Cynotherium
Species: †C. sardous, †C. malatestai
The Sardinian dhole (Cynotherium spp., especially C. sardous) was an extinct canid endemic to the islands of Sardinia and Corsica throughout the Pleistocene epoch.
Evolution:
Cynotherium first appears in the fossil record >800 thousand years ago.[1][2] It is believed that its ancestor was most likely Xenocyon, based on dental and mandibular characters. Cynotherium possessed hypercarnivorous dentition, a trait it most likely retained from a hypercarnivorous ancestor; no canid has ever evolved hypercarnivorous dentition without evolving the corresponding cranial characteristics. Only three Old World mainland canid genera evolved a hypercarnivorous diet: Xenocyon, Cuon, and Lycaon. Cuon lacks the third lower molar, leaving Xenocyon and Lycaon as possible candidates. Xenocyon is believed to be the more likely ancestor of the two because 1) it had a much wider geographic distribution across Eurasia (being found from China to England) and 2) Lycaon possesses strong anterior cusplets on p3 and p4, which both Xenocyon and Cynotherium lack.[3]
X. lycaonoides is found in several Eurasian localities from the late Early-Middle Pleistocene, and so this species is believed to be the ancestor of Cynotherium, appearing in Sardinia-Corsica around this time.[3]
Skeleton and outline of Cynotherium sardous in the foreground, with its ancestor Xenocyon lycaonoides in the background. Figure from [4]
Description and paleobiology:
Cynotherium sardous weighed ~10 kg, the size of an average jackal.[4] It possessed a hypercarnivorous dentition like its ancestor Xenocyon. However, unlike other hypercarnivorous canids, its cranial build suggests that it was not adapted to hunt large prey.[3][4] Cynotherium’s skull had a low sagittal crest, a wide postorbital constriction, weak zygomatic arches, and a slender mandible. This suite of characters is more typical of canids with a hypocarnivorous diet, making for an unusual combination with its hypercarnivorous teeth.[3]
Instead, Cynotherium displays a suite of adaptations pointing towards a specialization for small prey to a degree unseen in modern canids. First, Cynotherium was much smaller than its ancestor X. lycaonoides, weighing only ~10 kg. Carnivores that weigh less than 21 kg will generally hunt prey less than half of their own body mass, so Cynotherium was well able to fulfill its energetic requirements by hunting small prey.[4]
Second, the mastoid process was very enlarged and positioned laterally, being mostly insertion area for the M. obliquus capitis cranialis. This muscle continued its insertion further upward on the dorsal nuchal line. Because the anterior portion of the atlas wing was reduced, this meant that the muscle fibers of the M. obliquus capitis cranialis were oriented more ventrolaterally in Cynotherium. This suggests the neck was strong in rotation. Furthermore, the ventral surface of the basioccipital was proportionately broader than in modern canids, with the two rugose fossae for neck muscle attachment being deep and wide. This meant powerful motions for flexing the head and neck joint and drawing the neck downwards. Overall, Cynotherium had stronger neck movements than any extant canid, including in rotation, extension, and flexion of the head-neck joint, as well as for raising and lowering the head. Additionally, the neck was held lower than in Canis, and the third cervical vertebra had a prominent spinous process (in Canis the fourth vertebra does, and in Cuon the fifth). The powerful neck muscles meant strong and swift movements when catching fast-moving, small prey.[4]
Shoulder flexor muscle insertions on the humerus and scapula were well developed in Cynotherium. There were also well developed attachment areas for the triceps on the scapula, humerus, and ulna, such that this muscle was more important to Cynotherium than in any other canid. This was accompanied by an equally well developed M. anconeus, an elbow extensor. The powerful flexion and extension muscles of the forelimb, as well as a flexed elbow, point towards an animal that could crouch down to stalk its prey.[4] The legs, especially the front limbs, were also relatively short.[3]
An analysis of the petrosal bone of Cynotherium sardous indicates that it had poor hearing and echolocalization abilities, being limited to hearing high-frequency sounds and unable to hear anything below 250 Hz. The poor hearing and echolocalization abilities could be a result of the lack of predators and competition, as well as the abundance of prey such as Prolagus sardus. The specialization for hearing high-frequency noises could be reflected as another adaptation to hearing its preferred small prey.[5]
Taken together, Cynotherium sardous was a small prey specialist canid. The powerful extension of the elbow joint and flexion of the humero-scapular joint, short limbs, and neck held low are consistent with it stalking its quarry, similar to modern canids that hunt small prey. The strong shoulder flexors suggest powerful, extremely fast forward thrusts to grab its prey. The strong neck muscles emphasizing rotational and lateral movements point towards quick, powerful lateral movements to catch fast, small prey escaping with random movements or in zigzag patterns.[4] The hypercarnivorous dentition and the lightly built skull and jaws indicate feeding on small, swift prey and carrion only.[3][4] No living canid exhibits the same locomotory and neck adaptations to the same degree that Cynotherium does.[4] The high specialization on small prey is a result of the abundance of small prey on Sardinia, such as Prolagus sardus.[3]
Extinction:
The most recent remains of Cynotherium sardous are >1,000 years older than the first documented dates for human presence on Sardinia and Corsica. However, due to the long survival of Cynotherium on the island, as well as the timing of its most recent remains, it is reasonable to assume that it was present when humans first arrived on Sardinia and Corsica.[2] The exact cause of extinction is unknown.
References:
[1] Madurell-Malapeira, J., Palombo, M. R., & Sotnikova, M. (2015). Cynotherium malatestai, sp. nov. (Carnivora, Canidae) from the early middle Pleistocene deposits of Grotta dei Fiori (Sardinia, Western Mediterranean). Journal of vertebrate paleontology, 35(4), e943400.
[2] Valenzuela, A., Torres-Roig, E., Zoboli, D., Pillola, G. L., & Alcover, J. A. (2022). Asynchronous ecological upheavals on the Western Mediterranean islands: New insights on the extinction of their autochthonous small mammals. The Holocene, 32(3), 137-146.
[3] Lyras, G. A., Geer, A. A. V. D., Dermitzakis, M. D., & De Vos, J. (2006). Cynotherium sardous, an insular canid (Mammalia: Carnivora) from the Pleistocene of Sardinia (Italy), and its origin. Journal of Vertebrate Paleontology, 26(3), 735-745.
[4] Lyras, G., & Van der Geer, A. A. E. (2006). Adaptations of the Pleistocene island canid Cynotherium sardous (Sardinia, Italy) for hunting small prey. Cranium, 23(1), 51-60.
[5] Zedda, M., Brunetti, A., & Palombo, M. R. (2022). First Attempt to Infer Sound Hearing and Its Paleoenvironmental Implications in the Extinct Insular Canid Cynotherium sardous Studiati, 1857 (Sardinia, Italy). Animals, 12(7), 833.
Life reconstruction of Cynotherium sardous hunting the Sardinian pika (Prolagus sardus). © @ Peter Schouten (click here-> to view the larger image this is a part of).
Temporal range: Quaternary; Late Calabrian to Upper Pleistocene (>800-13.5 kya[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
(unranked): Pegasoferae
(unranked): Zooamata
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: Caniformia
Clade: Canoidea
Infraorder: Cynoidea
Family: Canidae
Subfamily: Canine
Tribe: Canini
Genus: †Cynotherium
Species: †C. sardous, †C. malatestai
The Sardinian dhole (Cynotherium spp., especially C. sardous) was an extinct canid endemic to the islands of Sardinia and Corsica throughout the Pleistocene epoch.
Evolution:
Cynotherium first appears in the fossil record >800 thousand years ago.[1][2] It is believed that its ancestor was most likely Xenocyon, based on dental and mandibular characters. Cynotherium possessed hypercarnivorous dentition, a trait it most likely retained from a hypercarnivorous ancestor; no canid has ever evolved hypercarnivorous dentition without evolving the corresponding cranial characteristics. Only three Old World mainland canid genera evolved a hypercarnivorous diet: Xenocyon, Cuon, and Lycaon. Cuon lacks the third lower molar, leaving Xenocyon and Lycaon as possible candidates. Xenocyon is believed to be the more likely ancestor of the two because 1) it had a much wider geographic distribution across Eurasia (being found from China to England) and 2) Lycaon possesses strong anterior cusplets on p3 and p4, which both Xenocyon and Cynotherium lack.[3]
X. lycaonoides is found in several Eurasian localities from the late Early-Middle Pleistocene, and so this species is believed to be the ancestor of Cynotherium, appearing in Sardinia-Corsica around this time.[3]
Skeleton and outline of Cynotherium sardous in the foreground, with its ancestor Xenocyon lycaonoides in the background. Figure from [4]
Description and paleobiology:
Cynotherium sardous weighed ~10 kg, the size of an average jackal.[4] It possessed a hypercarnivorous dentition like its ancestor Xenocyon. However, unlike other hypercarnivorous canids, its cranial build suggests that it was not adapted to hunt large prey.[3][4] Cynotherium’s skull had a low sagittal crest, a wide postorbital constriction, weak zygomatic arches, and a slender mandible. This suite of characters is more typical of canids with a hypocarnivorous diet, making for an unusual combination with its hypercarnivorous teeth.[3]
Instead, Cynotherium displays a suite of adaptations pointing towards a specialization for small prey to a degree unseen in modern canids. First, Cynotherium was much smaller than its ancestor X. lycaonoides, weighing only ~10 kg. Carnivores that weigh less than 21 kg will generally hunt prey less than half of their own body mass, so Cynotherium was well able to fulfill its energetic requirements by hunting small prey.[4]
Second, the mastoid process was very enlarged and positioned laterally, being mostly insertion area for the M. obliquus capitis cranialis. This muscle continued its insertion further upward on the dorsal nuchal line. Because the anterior portion of the atlas wing was reduced, this meant that the muscle fibers of the M. obliquus capitis cranialis were oriented more ventrolaterally in Cynotherium. This suggests the neck was strong in rotation. Furthermore, the ventral surface of the basioccipital was proportionately broader than in modern canids, with the two rugose fossae for neck muscle attachment being deep and wide. This meant powerful motions for flexing the head and neck joint and drawing the neck downwards. Overall, Cynotherium had stronger neck movements than any extant canid, including in rotation, extension, and flexion of the head-neck joint, as well as for raising and lowering the head. Additionally, the neck was held lower than in Canis, and the third cervical vertebra had a prominent spinous process (in Canis the fourth vertebra does, and in Cuon the fifth). The powerful neck muscles meant strong and swift movements when catching fast-moving, small prey.[4]
Shoulder flexor muscle insertions on the humerus and scapula were well developed in Cynotherium. There were also well developed attachment areas for the triceps on the scapula, humerus, and ulna, such that this muscle was more important to Cynotherium than in any other canid. This was accompanied by an equally well developed M. anconeus, an elbow extensor. The powerful flexion and extension muscles of the forelimb, as well as a flexed elbow, point towards an animal that could crouch down to stalk its prey.[4] The legs, especially the front limbs, were also relatively short.[3]
An analysis of the petrosal bone of Cynotherium sardous indicates that it had poor hearing and echolocalization abilities, being limited to hearing high-frequency sounds and unable to hear anything below 250 Hz. The poor hearing and echolocalization abilities could be a result of the lack of predators and competition, as well as the abundance of prey such as Prolagus sardus. The specialization for hearing high-frequency noises could be reflected as another adaptation to hearing its preferred small prey.[5]
Taken together, Cynotherium sardous was a small prey specialist canid. The powerful extension of the elbow joint and flexion of the humero-scapular joint, short limbs, and neck held low are consistent with it stalking its quarry, similar to modern canids that hunt small prey. The strong shoulder flexors suggest powerful, extremely fast forward thrusts to grab its prey. The strong neck muscles emphasizing rotational and lateral movements point towards quick, powerful lateral movements to catch fast, small prey escaping with random movements or in zigzag patterns.[4] The hypercarnivorous dentition and the lightly built skull and jaws indicate feeding on small, swift prey and carrion only.[3][4] No living canid exhibits the same locomotory and neck adaptations to the same degree that Cynotherium does.[4] The high specialization on small prey is a result of the abundance of small prey on Sardinia, such as Prolagus sardus.[3]
Extinction:
The most recent remains of Cynotherium sardous are >1,000 years older than the first documented dates for human presence on Sardinia and Corsica. However, due to the long survival of Cynotherium on the island, as well as the timing of its most recent remains, it is reasonable to assume that it was present when humans first arrived on Sardinia and Corsica.[2] The exact cause of extinction is unknown.
References:
[1] Madurell-Malapeira, J., Palombo, M. R., & Sotnikova, M. (2015). Cynotherium malatestai, sp. nov. (Carnivora, Canidae) from the early middle Pleistocene deposits of Grotta dei Fiori (Sardinia, Western Mediterranean). Journal of vertebrate paleontology, 35(4), e943400.
[2] Valenzuela, A., Torres-Roig, E., Zoboli, D., Pillola, G. L., & Alcover, J. A. (2022). Asynchronous ecological upheavals on the Western Mediterranean islands: New insights on the extinction of their autochthonous small mammals. The Holocene, 32(3), 137-146.
[3] Lyras, G. A., Geer, A. A. V. D., Dermitzakis, M. D., & De Vos, J. (2006). Cynotherium sardous, an insular canid (Mammalia: Carnivora) from the Pleistocene of Sardinia (Italy), and its origin. Journal of Vertebrate Paleontology, 26(3), 735-745.
[4] Lyras, G., & Van der Geer, A. A. E. (2006). Adaptations of the Pleistocene island canid Cynotherium sardous (Sardinia, Italy) for hunting small prey. Cranium, 23(1), 51-60.
[5] Zedda, M., Brunetti, A., & Palombo, M. R. (2022). First Attempt to Infer Sound Hearing and Its Paleoenvironmental Implications in the Extinct Insular Canid Cynotherium sardous Studiati, 1857 (Sardinia, Italy). Animals, 12(7), 833.
