Ankistrodon es un género de arcosaurio que vivió en el Triásico inferior (hace cerca de 248 millones de años) cuyos fósiles fueron encontrados en la India, el cual fue inicialmente considerado como un dinosaurio. Más tarde fue considerado como unarcosauriforme proterosúquido. La especie tipo es A. indicus, descrita por el prolífico zoológo británico Thomas Henry Huxley en 1865. Una autoridad en la década de 1970 clasificó a Ankistrodon como un sinónimo menor de Proterosuchus.
Ankistrodon or Epicampodon, but not Agkistrodon or Ancistrodon ...
... which was renamed Ankistrodus then Grypodon. Yay for taxonomy. Today we feature another ex-theropod taxon, from the soon-to-be-uploaded (as in, before 2011) Ex-Theropoda section of my site.
Ankistrodon Huxley, 1865
= Epicampodon Lydekker, 1885
A. indicus Huxley, 1865
= Epicampodon indicus (Huxley, 1865) Lydekker, 1885
= Thecodontosaurus indicus (Huxley, 1865) Huene, 1908
= Chasmatosaurus indicus (Huxley, 1865) Huene, 1942
Early Scythian, Early Triassic
Panchet Formation, India
Holotype- (GSI coll.) dentary fragment, two teeth
Referred- ?(GSI coll.) cervical vertebrae, anterior dorsal vertebrae, sacral vertebrae, proximal caudal vertebrae (Huene, 1942)
Comments- Huxley named and described the holotype, believing it to be a thecodont most similar to the parasuchian Clepsysaurus based on the presence of only distal serrations. He later (1870) referred Thecodontia to Dinosauria, leading him to refer Ankistrodon to the latter clade. Seeley (1880) mentioned the genus as a dinosaur related to Megalosaurus. He later (1885) created the genus Epicampodon for the taxon, since he incorrectly thought Ankistrodon was preoccupied by the recent viperid genus Agkistrodon Palisot de Beauvois, 1799 (or its own unjustified emmendation Ancistrodon Wagler, 1830; or the pycnodontiform fish Ancistrodon Roemer, 1849, which was renamed Ankistrodus then Grypodon). Seeley (1888) illustrated Epicampodon as an anchisaurid theropod, while Nopcsa (1901) listed it as an anchisaurine megalosaurid. It was listed as a zanclodontid theropod by Zittel (1890) and Huene (1902), who incorrectly believed it to be from the Late Triassic Maleri beds. Huene (1906) stated that the species was probably referrable to Thecodontosaurus, though he did not explicitly list the new combination until 1908. In that work he called it Thecodontosaurus(?) indicus, believing it to be most similar to Paleosaurus (his Thecodontosaurus cylindrodon). Das-Gupta (1931) thought the species was similar to his new theropod Orthogoniosaurus in having only distal serrations and having a straight distal edge (actually caused by apical breakage in indicus), placing both in Anchisauridae within Theropoda.
Huene still referred Epicampodon to Saurischia in 1940, but in 1942 recognized it was a more basal archosauriform and made it a species of Chasmatosaurus. This was followed by Tatarinov (1961), but Charig et al. (1976) correctly noted Ankistrodon has priority over Chasmatosaurus (and its senior synonym Proterosuchus). Charig and Reig (1970) and Reig (1970) considered it an indeterminate proterosuchian. Romer (1972) considered the material to be Proterosuchus without explicitly naming the new combination. Most recently, Charig et al. (1976) considered Ankistrodon a seemingly valid genus of proterosuchid, which was followed by Olshevsky (1991). While the presence of serrations does indicate an archosauriform, the Early Triassic age excludes parasuchians and theropods, and the recurved crowns exclude a relationship to sauropodomorphs like Thecodontosaurus or Anchisaurus, evidence supporting a close relationship with Proterosuchus was perhaps only given by Huene (1942), prior to the discovery of a large amount of 'proterosuchian' diversity. Recent analyses suggest that the traditional Proterosuchidae is a paraphyletic grade of basal archosauriforms, so Ankistrodon is here placed in Archosauriformes until further studies on mandibular and dental variation are performed.
Huxley (1865) also described vertebrae as belonging to Dicynodon orientalis (now Lystrosaurus murrayi), which were recognized by Huene (1942) as being archosauriform and referred to his Chasmatosaurus indicus. As the vertebrae cannot be compared to the type jaw fragment, Charig and Reig (1970) merely called them cf. Chasmatosaurus sp..
Ankistrodon Huxley, 1865
= Epicampodon Lydekker, 1885
A. indicus Huxley, 1865
= Epicampodon indicus (Huxley, 1865) Lydekker, 1885
= Thecodontosaurus indicus (Huxley, 1865) Huene, 1908
= Chasmatosaurus indicus (Huxley, 1865) Huene, 1942
Early Scythian, Early Triassic
Panchet Formation, India
Holotype- (GSI coll.) dentary fragment, two teeth
Referred- ?(GSI coll.) cervical vertebrae, anterior dorsal vertebrae, sacral vertebrae, proximal caudal vertebrae (Huene, 1942)
 |
| Holotype of Ankistrodon indicus (GSI coll.) in (A) lateral and (B) posterior views, with (C) a cross section of a tooth. After Huxley, 1865. |
Comments- Huxley named and described the holotype, believing it to be a thecodont most similar to the parasuchian Clepsysaurus based on the presence of only distal serrations. He later (1870) referred Thecodontia to Dinosauria, leading him to refer Ankistrodon to the latter clade. Seeley (1880) mentioned the genus as a dinosaur related to Megalosaurus. He later (1885) created the genus Epicampodon for the taxon, since he incorrectly thought Ankistrodon was preoccupied by the recent viperid genus Agkistrodon Palisot de Beauvois, 1799 (or its own unjustified emmendation Ancistrodon Wagler, 1830; or the pycnodontiform fish Ancistrodon Roemer, 1849, which was renamed Ankistrodus then Grypodon). Seeley (1888) illustrated Epicampodon as an anchisaurid theropod, while Nopcsa (1901) listed it as an anchisaurine megalosaurid. It was listed as a zanclodontid theropod by Zittel (1890) and Huene (1902), who incorrectly believed it to be from the Late Triassic Maleri beds. Huene (1906) stated that the species was probably referrable to Thecodontosaurus, though he did not explicitly list the new combination until 1908. In that work he called it Thecodontosaurus(?) indicus, believing it to be most similar to Paleosaurus (his Thecodontosaurus cylindrodon). Das-Gupta (1931) thought the species was similar to his new theropod Orthogoniosaurus in having only distal serrations and having a straight distal edge (actually caused by apical breakage in indicus), placing both in Anchisauridae within Theropoda.
Huene still referred Epicampodon to Saurischia in 1940, but in 1942 recognized it was a more basal archosauriform and made it a species of Chasmatosaurus. This was followed by Tatarinov (1961), but Charig et al. (1976) correctly noted Ankistrodon has priority over Chasmatosaurus (and its senior synonym Proterosuchus). Charig and Reig (1970) and Reig (1970) considered it an indeterminate proterosuchian. Romer (1972) considered the material to be Proterosuchus without explicitly naming the new combination. Most recently, Charig et al. (1976) considered Ankistrodon a seemingly valid genus of proterosuchid, which was followed by Olshevsky (1991). While the presence of serrations does indicate an archosauriform, the Early Triassic age excludes parasuchians and theropods, and the recurved crowns exclude a relationship to sauropodomorphs like Thecodontosaurus or Anchisaurus, evidence supporting a close relationship with Proterosuchus was perhaps only given by Huene (1942), prior to the discovery of a large amount of 'proterosuchian' diversity. Recent analyses suggest that the traditional Proterosuchidae is a paraphyletic grade of basal archosauriforms, so Ankistrodon is here placed in Archosauriformes until further studies on mandibular and dental variation are performed.
Huxley (1865) also described vertebrae as belonging to Dicynodon orientalis (now Lystrosaurus murrayi), which were recognized by Huene (1942) as being archosauriform and referred to his Chasmatosaurus indicus. As the vertebrae cannot be compared to the type jaw fragment, Charig and Reig (1970) merely called them cf. Chasmatosaurus sp..
Aphanizocnemus es un género extinto de lagarto varanoide del Líbano. Era un reptil marino que vivió durante el Cretácico Superior. Ha sido frecuentemente clasificado en la familia Dolichosauridae siendo así un pariente cercano de las serpientes, aunque algunos estudios lo han situado como un pariente incluso más cercano a las serpientes que a los dolicosáuridos. Solo se conoce una especie de Aphanizocnemus, la especie tipo A. libanensis. A. libanensis fue nombrado en 1997 basándose en un único esqueleto completo.1
Aphanizocnemus medía cerca de 30 centímetros de largo, y la cola constituía más de la mitad de esa longitud. Las manos y pies eran muy grandes comparados con los huesos de las extremidades. La forma aplanada de las falanges, o huesos de los dedos, sugieren que las extremidades de Aphanizocnemus formaban aletas. Largas proyecciones óseas en la cola denominadas cheurones le daban a la cola una forma de aleta aplanada.Aphanizocnemus estaba bien adaptado para un estilo de vida acuático, y probablemente pasaba la mayor parte de su tiempo nadando en el fondo de las lagunas poco profundas.
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