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Encyclopedia Largest prehistoric animals Vol.1 Vertebrates part9 Reptiles ch.3 Crocodylomorpha - Ghavials and Dyrosaurids
Автор: valentint
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Последна промяна: 29.04.2019 23:37
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Последна промяна: 29.04.2019 23:37
Gavialoidea
1. Thoracosaurus 2. Toyotamaphimeia 3. Ikanogavialis 4. Rhamphosuchus 5. Gryposuchus
Gavialoidea contains the family Gavialidae and several more basal extinct forms such as Thoracosaurus and Eosuchus. Within Gavialidae are two subfamilies: Gavialinae, which includes the living gharial, and Gryposuchinae, which includes several extinct forms such as Gryposuchus and Aktiogavialis.
In addition to these groups, recent molecular studies consistently indicate that the false gharial (and by inference other related extinct forms) traditionally viewed as belonging to the crocodylian subfamily Tomistominae actually belong to Gavialoidea.As its name suggests, the false gharial was once thought to be only distantly related to the gharial despite its similar appearance. The false gharial and other tomistomines were traditionally classified within the superfamily Crocodyloidea as close relatives of crocodiles.
Larges Gavialidae is Rhamphosuchus, estimated at 10–13 metres (30–42 ft) in length.
Rhamphosuchus ("Beak crocodile") is an extinct relative of the modern false gharial. It inhabited what is now the Indian sub-continent in the Miocene. It is only known from incomplete sets of fossils, mostly teeth and skulls.
Traditionally, many palaeontologists estimated that it was one of the largest, if not the largest crocodylian that ever lived, reaching an estimated length of 15 to 18 m (50–60 ft). However, a more recent study suggests that the animal may have been 10–21 m in length, and therefore is not the largest known crocodylian.Another crocodylian, Purussaurus, from the Miocene of Peru and Brazil, is known from an equally incomplete fossil set. It is estimated to have been similar in length to the initial estimates at approximately 12 m. However, this would mean that it would have been somewhat larger in size if the more recent size estimates for Rhamphosuchus are correct. If the most recent estimate is correct, then several other extinct crocodylians also surpassed Rhamphosuchus in length, such as the Late Cretaceous alligatoroid Deinosuchus, the Early Cretaceous pholidosaurid Sarcosuchus, the Miocene gavialid Gryposuchus and the strange planktivorous Mourasuchus (a contemporary of Purussaurus), at 12 m, 11–12 m, 10.15 m, and 12 m, respectively.Rhamphosuchus probably had a more generalized predatory diet than the piscivory of other tomistomines.
Gryposuchus
Gryposuchus is an extinct genus of gavialoid crocodilian. It is the type genus of the subfamily Gryposuchinae. Fossils have been found from Argentina, Colombia, Venezuela, Brazil and the Peruvian Amazon. The genus existed during the early and middle Miocene epoch. One recently described species, G. croizati, grew to an estimated length of 10 metres (33 ft).
The type species of Gryposuchus is G. neogaeus. Specimens from this species were first described from Argentina in 1885, although it was referred to Ramphostoma at the time.It was assigned to the current genus in 1912 along with a newly described species, G. jessei.
Another species, G. colombianus, has been recovered from deposits in Colombia that date back to the Miocene and Pliocene epochs. This species, named in 1965, was originally referred to Gavialis. Fragmentary material of Gryposuchus from the Fitzcarrald Arch in the Peruvian Amazon dating back to the late middle Miocene bear a close resemblance to G. colombianus, but differ in rostrum proportions.
A new species, G. croizati, found from the upper Miocene Urumaco Formation in northwestern Venezuela, can be distinguished from other species of Gryposuchus on the basis of a reduced number of maxillary teeth, a slender parietal interfenestral bar, and widely separated and reduced palatine fenestrae, among other things. Based on measurements of the orbital cranial skeleton, the length of the animal has been estimated at around 10.15 m in length, with a total mass of about 1745 kg. Measuring the entire length of the skull from the end of the rostrum to the supraoccipital would result in a much larger size estimate, up to three times as great. However, because there is considerable variation seen in rostral proportions among crocodilians, the latter measurements are probably not an accurate way of estimating body mass and length.Despite this, the species is still one of the largest crocodilians known to have existed, and it may indeed have been the largest gavialoid to have ever existed if a recent revision in the estimated size of the large tomistomine Rhamphosuchus is correct (the genus was once considered to be 15 m in length; the new estimate puts it at approximately 10 m).
Some gryposuchines such as Siquisiquesuchus and Piscogavialis have been found from localities thought to have been deposited in coastal environments.The presence of Gryposuchus in the Urumaco Formation of Venezuela, which does include marine strata, lends credence to the idea that gryposuchines may have been living in coastal environments.However, certain localities where material from the species G. colombianus has been recovered, such as La Venta, Colombia, were clearly deposited in non-marine environments, speaking against the proposed coastal lifestyle hypothesis for all gryposuchines.
Euthecodon
Euthecodon is an extinct genus of long-snouted crocodyline crocodilians. It was common throughout much of Africa during the Neogene, with fossils being especially common in Kenya. It existed from the Early Miocene to the Early Pleistocene.
Euthecodon was large for a crocodilian. One specimen, LT 26306, found from the Turkana Basin, was estimated by skull length to have been around 10m long. It had a narrow rostrum that was unusually elongate with deeply scalloped dorsal margins. The skull table, however, was proportionally small and is almost square in shape. The jaws were lined with isodont, or slender, similarly sized and shaped, teeth. Unlike nearly all other crocodilians, Euthecodon possessed only four premaxillary teeth. Because they are sharp and bicarinate, they are believed to have been an adaptation for a piscivorous feeding habit, or a diet that included fish.
Collected material now known to be from Euthecodon was initially placed in the genus Tomistoma, of which the modern false gharial is a member. These specimens were described from the Pliocene Omo Group in Ethiopia. The genus Euthecodon was first named in 1920 on the basis of material found from Wadi Natrun, Egypt. This material was believed to have belonged to the same species as the specimens from Ethiopia, yet it appeared to be distinct from the genus Tomistoma. As a result, the material from Ethiopia was reassigned to the new genus along with the material from Egypt, with the species being named E. nitriae.
A new species, named E. brumpti, was found from Lothagam, Kenya and can be distinguished from E. nitriae by skull and rostral proportions as well as tooth count. E. brumpti is one of the most common fossil crocodylians found in the Turkana Basin, along with crocodiles referred to Rimasuchus lloydi. A complete articulated skull and mandible referrable to E. brumpti was found in situ from the Kaiyumung Member of the Nachukui Formation in Lothagam in 1992.
A shorter snouted species named E. arambourgi has been found from early Miocene deposits in Gebel Zelten, Libya. Classification of specimens from several localities across Africa are indeterminant at the species level, with material being found from the Sahabi Formation in Libya of early Pliocene age the Victoria Basin strata of Rusinga Island of early Miocene age early Miocene deposits in Ombo, Kenya and possibly the Albertine Rift sediments of the Congo of early Miocene age.
Euthecodon was originally considered a tomistomine crocodilian. It has even been suggested to be a direct offshoot of Eogavialis. However, it is now thought to be a crocodylid, having been allied with Rimasuchus, Osteolaemus, and Voay in the past.
Toyotamaphimeia
Toyotamaphimeia is an extinct genus of tomistomine, a crocodylian from the Pleistocene era of Japanese prehistory. It is closely related to the False Gharial, and lived 400,000 years ago. This relationship is reflected in its original description as a member of the same genus, Tomistoma. It was a fairly large crocodylian with a 1 m (3.3 ft) skull and a total length up to 8 m (26 ft). Like the False Gharial, it had a relatively narrow snout suitable for snapping up fish, though not so specialized as that of the gharial.T. machikanensis is considered a link in the chain showing the spread of tomistomine crocodylians spreading from Europe into South East Asia. While the modern False Gharial is a fresh water species, many of it"s ancestors were creatures of the sea coast and estuary. It is unknown if T. machikanensis
The type specimen takes the form of a complete skeleton was found accidentally in a four-hundred fifty thousand year old layer of clay during construction of Osaka University"s Toyonaka campus in 1965. Judging by the fossil pollen found with it, the temperature was warm and temperate at the time of the animal"s death. In June of 2014 the skeleton was declared a Japanese national treasure.
The type specimen was found in the Osaka Prefecture of Central Japan and shows multiple abnormalities. A third of the mandible was amputated and showed signs of healing. The right tibia and fibula were fractured, and each of them was later fused in dislocated position with calluses. Additionally, there are two puncture marks on a dermal scute. Based on the shape of these injuries and the creatures found where this animal lived, and the behavior of extant crocodilians, it seems likely the individual survived its injuries sustained during multiple intraspecific fights for territoriality or mating.
Dyrosauridae
1. Acherontisuchus 2. Phosphatosaurus 3. Chenanisuchus 4. Oceanosuchus 5. Guarinisuchus
Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Late Cretaceous (Maastrichtian) to the Eocene. Dyrosaurid fossils are globally distributed, having been found in Africa, Asia, Europe, North America and South America. Over a dozen species are currently known, varying greatly in overall size and cranial shape. All were presumably aquatic, with species inhabiting both freshwater and marine environments. Ocean-dwelling dyrosaurids were among the few marine reptiles to survive the Cretaceous–Paleogene extinction event.
1. Thoracosaurus 2. Toyotamaphimeia 3. Ikanogavialis 4. Rhamphosuchus 5. Gryposuchus
Gavialoidea contains the family Gavialidae and several more basal extinct forms such as Thoracosaurus and Eosuchus. Within Gavialidae are two subfamilies: Gavialinae, which includes the living gharial, and Gryposuchinae, which includes several extinct forms such as Gryposuchus and Aktiogavialis.
In addition to these groups, recent molecular studies consistently indicate that the false gharial (and by inference other related extinct forms) traditionally viewed as belonging to the crocodylian subfamily Tomistominae actually belong to Gavialoidea.As its name suggests, the false gharial was once thought to be only distantly related to the gharial despite its similar appearance. The false gharial and other tomistomines were traditionally classified within the superfamily Crocodyloidea as close relatives of crocodiles.
Larges Gavialidae is Rhamphosuchus, estimated at 10–13 metres (30–42 ft) in length.
Rhamphosuchus ("Beak crocodile") is an extinct relative of the modern false gharial. It inhabited what is now the Indian sub-continent in the Miocene. It is only known from incomplete sets of fossils, mostly teeth and skulls.
Traditionally, many palaeontologists estimated that it was one of the largest, if not the largest crocodylian that ever lived, reaching an estimated length of 15 to 18 m (50–60 ft). However, a more recent study suggests that the animal may have been 10–21 m in length, and therefore is not the largest known crocodylian.Another crocodylian, Purussaurus, from the Miocene of Peru and Brazil, is known from an equally incomplete fossil set. It is estimated to have been similar in length to the initial estimates at approximately 12 m. However, this would mean that it would have been somewhat larger in size if the more recent size estimates for Rhamphosuchus are correct. If the most recent estimate is correct, then several other extinct crocodylians also surpassed Rhamphosuchus in length, such as the Late Cretaceous alligatoroid Deinosuchus, the Early Cretaceous pholidosaurid Sarcosuchus, the Miocene gavialid Gryposuchus and the strange planktivorous Mourasuchus (a contemporary of Purussaurus), at 12 m, 11–12 m, 10.15 m, and 12 m, respectively.Rhamphosuchus probably had a more generalized predatory diet than the piscivory of other tomistomines.
Gryposuchus
Gryposuchus is an extinct genus of gavialoid crocodilian. It is the type genus of the subfamily Gryposuchinae. Fossils have been found from Argentina, Colombia, Venezuela, Brazil and the Peruvian Amazon. The genus existed during the early and middle Miocene epoch. One recently described species, G. croizati, grew to an estimated length of 10 metres (33 ft).
The type species of Gryposuchus is G. neogaeus. Specimens from this species were first described from Argentina in 1885, although it was referred to Ramphostoma at the time.It was assigned to the current genus in 1912 along with a newly described species, G. jessei.
Another species, G. colombianus, has been recovered from deposits in Colombia that date back to the Miocene and Pliocene epochs. This species, named in 1965, was originally referred to Gavialis. Fragmentary material of Gryposuchus from the Fitzcarrald Arch in the Peruvian Amazon dating back to the late middle Miocene bear a close resemblance to G. colombianus, but differ in rostrum proportions.
A new species, G. croizati, found from the upper Miocene Urumaco Formation in northwestern Venezuela, can be distinguished from other species of Gryposuchus on the basis of a reduced number of maxillary teeth, a slender parietal interfenestral bar, and widely separated and reduced palatine fenestrae, among other things. Based on measurements of the orbital cranial skeleton, the length of the animal has been estimated at around 10.15 m in length, with a total mass of about 1745 kg. Measuring the entire length of the skull from the end of the rostrum to the supraoccipital would result in a much larger size estimate, up to three times as great. However, because there is considerable variation seen in rostral proportions among crocodilians, the latter measurements are probably not an accurate way of estimating body mass and length.Despite this, the species is still one of the largest crocodilians known to have existed, and it may indeed have been the largest gavialoid to have ever existed if a recent revision in the estimated size of the large tomistomine Rhamphosuchus is correct (the genus was once considered to be 15 m in length; the new estimate puts it at approximately 10 m).
Some gryposuchines such as Siquisiquesuchus and Piscogavialis have been found from localities thought to have been deposited in coastal environments.The presence of Gryposuchus in the Urumaco Formation of Venezuela, which does include marine strata, lends credence to the idea that gryposuchines may have been living in coastal environments.However, certain localities where material from the species G. colombianus has been recovered, such as La Venta, Colombia, were clearly deposited in non-marine environments, speaking against the proposed coastal lifestyle hypothesis for all gryposuchines.
Euthecodon
Euthecodon is an extinct genus of long-snouted crocodyline crocodilians. It was common throughout much of Africa during the Neogene, with fossils being especially common in Kenya. It existed from the Early Miocene to the Early Pleistocene.
Euthecodon was large for a crocodilian. One specimen, LT 26306, found from the Turkana Basin, was estimated by skull length to have been around 10m long. It had a narrow rostrum that was unusually elongate with deeply scalloped dorsal margins. The skull table, however, was proportionally small and is almost square in shape. The jaws were lined with isodont, or slender, similarly sized and shaped, teeth. Unlike nearly all other crocodilians, Euthecodon possessed only four premaxillary teeth. Because they are sharp and bicarinate, they are believed to have been an adaptation for a piscivorous feeding habit, or a diet that included fish.
Collected material now known to be from Euthecodon was initially placed in the genus Tomistoma, of which the modern false gharial is a member. These specimens were described from the Pliocene Omo Group in Ethiopia. The genus Euthecodon was first named in 1920 on the basis of material found from Wadi Natrun, Egypt. This material was believed to have belonged to the same species as the specimens from Ethiopia, yet it appeared to be distinct from the genus Tomistoma. As a result, the material from Ethiopia was reassigned to the new genus along with the material from Egypt, with the species being named E. nitriae.
A new species, named E. brumpti, was found from Lothagam, Kenya and can be distinguished from E. nitriae by skull and rostral proportions as well as tooth count. E. brumpti is one of the most common fossil crocodylians found in the Turkana Basin, along with crocodiles referred to Rimasuchus lloydi. A complete articulated skull and mandible referrable to E. brumpti was found in situ from the Kaiyumung Member of the Nachukui Formation in Lothagam in 1992.
A shorter snouted species named E. arambourgi has been found from early Miocene deposits in Gebel Zelten, Libya. Classification of specimens from several localities across Africa are indeterminant at the species level, with material being found from the Sahabi Formation in Libya of early Pliocene age the Victoria Basin strata of Rusinga Island of early Miocene age early Miocene deposits in Ombo, Kenya and possibly the Albertine Rift sediments of the Congo of early Miocene age.
Euthecodon was originally considered a tomistomine crocodilian. It has even been suggested to be a direct offshoot of Eogavialis. However, it is now thought to be a crocodylid, having been allied with Rimasuchus, Osteolaemus, and Voay in the past.
Toyotamaphimeia
Toyotamaphimeia is an extinct genus of tomistomine, a crocodylian from the Pleistocene era of Japanese prehistory. It is closely related to the False Gharial, and lived 400,000 years ago. This relationship is reflected in its original description as a member of the same genus, Tomistoma. It was a fairly large crocodylian with a 1 m (3.3 ft) skull and a total length up to 8 m (26 ft). Like the False Gharial, it had a relatively narrow snout suitable for snapping up fish, though not so specialized as that of the gharial.T. machikanensis is considered a link in the chain showing the spread of tomistomine crocodylians spreading from Europe into South East Asia. While the modern False Gharial is a fresh water species, many of it"s ancestors were creatures of the sea coast and estuary. It is unknown if T. machikanensis
The type specimen takes the form of a complete skeleton was found accidentally in a four-hundred fifty thousand year old layer of clay during construction of Osaka University"s Toyonaka campus in 1965. Judging by the fossil pollen found with it, the temperature was warm and temperate at the time of the animal"s death. In June of 2014 the skeleton was declared a Japanese national treasure.
The type specimen was found in the Osaka Prefecture of Central Japan and shows multiple abnormalities. A third of the mandible was amputated and showed signs of healing. The right tibia and fibula were fractured, and each of them was later fused in dislocated position with calluses. Additionally, there are two puncture marks on a dermal scute. Based on the shape of these injuries and the creatures found where this animal lived, and the behavior of extant crocodilians, it seems likely the individual survived its injuries sustained during multiple intraspecific fights for territoriality or mating.
Dyrosauridae
1. Acherontisuchus 2. Phosphatosaurus 3. Chenanisuchus 4. Oceanosuchus 5. Guarinisuchus
Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Late Cretaceous (Maastrichtian) to the Eocene. Dyrosaurid fossils are globally distributed, having been found in Africa, Asia, Europe, North America and South America. Over a dozen species are currently known, varying greatly in overall size and cranial shape. All were presumably aquatic, with species inhabiting both freshwater and marine environments. Ocean-dwelling dyrosaurids were among the few marine reptiles to survive the Cretaceous–Paleogene extinction event.
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