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Ikanogavialis

January 01, 1970

Ikanogavialis is an extinct genus of gavialid crocodilian. Fossils have been found in the Urumaco Formation in Urumaco, Venezuela and the Solimões Formation of Brazil. The strata from which remains are found are late Miocene in age, rather than Pliocene as was once thought.[2] A possible member of this genus survived into the Late Holocene on Muyua or Woodlark Island in Papua New Guinea.

Ikanogavialis
Temporal range: Late Miocene, 11.6–6.8 Ma[1]
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Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Clade: Archosauriformes
Order: Crocodilia
Family: Gavialidae
Subfamily: †Gryposuchinae
Genus: †Ikanogavialis
Sill 1970
Species

Description edit

Ikanogavialis had a dorsoventrally deep snout and a distinctive notch between the dentary and maxillary alveoli.[3] The external nares projected anterodorsally from the rostrum. This can be seen as a plesiomorphic characteristic in crocodilians, but given that the earliest gavialoids possessed dorsally projecting external nares, this feature can be seen as having been a reversal from the gavialoid apomorphy back to the crocodilian plesiomorphy rather than having been directly obtained from an early crocodilian ancestor.

Species edit

The type species of Ikanogavialis is I. gameroi. It was named in 1970 from material found from the Urumaco formation of Venezuela, South America.

Additionally, a Pleistocene gavialoid found on Woodlark Island of Papua New Guinea was initially named Gavialis papuensis in 1905, but has since been proposed to be a member of Ikanogavialis,[4] although the poor quality of the preserved material makes it difficult to determine.[1]

Paleobiology edit

Ikanogavialis may have lived in a coastal paleoenvironment along with other gavialids such as Gryposuchus. The strata of the Urumaco formation were deposited in both marine and fluvial settings, although it is unclear to which portion both genera belong.[5][6] Other gavialoids such as Siquisiquesuchus and Piscogavialis are known to have lived in coastal environments, and it is likely that extant freshwater gavialoids such as Gavialis may have originated from these coastal forms.[7][8] Ikanogavialis also existed with many other crocodilians in Venezuela during the late Miocene including the giant caiman Purussaurus and an extinct species of Melanosuchus.[9]

"Gavialis" / Ikanogavialis papuensis was similarly fully marine, having been found in association with sea turtles and sirenians. It represents the youngest fully marine crocodilian to date.[10]

Phylogeny edit

A phylogenetic analysis conducted in a 2007 study found Gryposuchinae to include the genera Aktiogavialis, Gryposuchus, Ikanogavialis, Piscogavialis, and Siquisiquesuchus. Below is a cladogram from the 2007 analysis showing the phylogenetic relationships of gryposuchines among gavialoids:[11]

Alternatively, a 2018 tip dating study by Lee & Yates simultaneously using morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data indicated that the members of Gryposuchinae may in fact be paraphyletic and rather an evolutionary grade towards Gavialis and the gharial, as shown in the cladogram below:[12]

Notes and references edit

  1. ^ a b Rio, Jonathan P.; Mannion, Philip D. (6 September 2021). "Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem". PeerJ. 9: e12094. doi:10.7717/peerj.12094. PMC 8428266. PMID 34567843.
  2. ^ Langston, W.; Gasparini, Z. (1997). "Crocodilians, Gryposuchus, and the South American gavials". In Kay, R. F.; Madden, R. H.; Cifelli, R. L.; Flynn, J. J. (eds.). Vertebrate Paleontology in the Neotropics: The Miocene fauna of La Venta, Colombia. Washington, D.C.: Smithsonian Institution Press. pp. 113–154. ISBN 1-56098-418-X.
  3. ^ Sill, W. D. (1970). "Nota preliminar sobre un nuevo gavial del Plioceno de Venezuela y una discusion de los gaviales sudamericanos" [Preliminary note on a new gharial Pliocene of Venezuela and a discussion of the South American gavials]. Ameghiniana. 7: 151–159.
  4. ^ Martin, Jeremy E.; Buffetaut, Eric; Naksri, Wilailuck; Lauprasert, Komsorn; Claude, Julien (18 September 2012). "Gavialis from the Pleistocene of Thailand and Its Relevance for Drainage Connections from India to Java". PLOS One. 7 (9): e44541. Bibcode:2012PLoSO...744541M. doi:10.1371/journal.pone.0044541. PMC 3445548. PMID 23028557.
  5. ^ Linares, O. J. (2004). "Bioestratigrafia de la fauna de mamiferos de las Formaciones Socorro, Urumaco y Codore (Mioceno Medio–Plioceno Temprano) de la region de Urumaco, Falcon, Venezuela". Paleobiologia Neotropical. 1: 1–26.
  6. ^ Sánchez-Villagra, M. R.; Aguilera, O. A. (2006). "Neogene vertebrates from Urumaco, Falcón State, Venezuela: diversity and significance". Journal of Systematic Palaeontology. 4 (3): 213–220. doi:10.1017/S1477201906001829. S2CID 84357359.
  7. ^ Kraus, R. (1998). "The cranium of Piscogavialis jugaliperforatus n. gen., n. sp. (Gavialidae, Crocodylia) from the Miocene of Peru". Paläontologische Zeitschrift. 72 (3–4): 389–406. doi:10.1007/BF02988368. S2CID 84214781.
  8. ^ Brochu, C. A.; Rincon, A. D. (2004). "A gavialoid crocodylian from the Lower Miocene of Venezuela". Special Papers in Palaeontology. 71: 61–78.
  9. ^ Aguilera, O. A.; Driff, D.; Bocquentin-Villanueva, J. (2006). "A new giant Purussaurus (Crocodyliformes, Alligatoridae) from the Upper Miocene Urumaco Formation, Venezuela". Journal of Systematic Palaeontology. 4 (3): 221–232. doi:10.1017/S147720190600188X. S2CID 85950121.
  10. ^ Molnar, R. E. (1982). "A longirostrine crocodilian from Murua (Woodlark), Solomon Sea". Memoirs of the Queensland Museum. 20: 675–685.
  11. ^ Vélez-Juarbe, Jorge; Brochu, C.A.; Santos, H. (2007). "A gharial from the Oligocene of Puerto Rico: transoceanic dispersal in the history of a non-marine reptile". Proceedings of the Royal Society B. 274 (1615): 1245–1254. doi:10.1098/rspb.2006.0455. PMC 2176176. PMID 17341454.
  12. ^ Michael S. Y. Lee; Adam M. Yates (27 June 2018). "Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil". Proceedings of the Royal Society B. 285 (1881). doi:10.1098/rspb.2018.1071. PMC 6030529. PMID 30051855.

External links edit

January 01, 1970
ikanogavialis, extinct, genus, gavialid, crocodilian, fossils, have, been, found, urumaco, formation, urumaco, venezuela, solimões, formation, brazil, strata, from, which, remains, found, late, miocene, rather, than, pliocene, once, thought, possible, member, . Ikanogavialis is an extinct genus of gavialid crocodilian Fossils have been found in the Urumaco Formation in Urumaco Venezuela and the Solimoes Formation of Brazil The strata from which remains are found are late Miocene in age rather than Pliocene as was once thought 2 A possible member of this genus survived into the Late Holocene on Muyua or Woodlark Island in Papua New Guinea IkanogavialisTemporal range Late Miocene 11 6 6 8 Ma 1 PreꞒ Ꞓ O S D C P T J K Pg N Scientific classification Domain Eukaryota Kingdom Animalia Phylum Chordata Class Reptilia Clade Archosauromorpha Clade Archosauriformes Order Crocodilia Family Gavialidae Subfamily Gryposuchinae Genus IkanogavialisSill 1970 Species I gameroi Sill 1970 type I papuensis De Vis 1905 originally Gavialis papuensis Contents 1 Description 2 Species 3 Paleobiology 4 Phylogeny 5 Notes and references 6 External linksDescription editIkanogavialis had a dorsoventrally deep snout and a distinctive notch between the dentary and maxillary alveoli 3 The external nares projected anterodorsally from the rostrum This can be seen as a plesiomorphic characteristic in crocodilians but given that the earliest gavialoids possessed dorsally projecting external nares this feature can be seen as having been a reversal from the gavialoid apomorphy back to the crocodilian plesiomorphy rather than having been directly obtained from an early crocodilian ancestor Species editThe type species of Ikanogavialis is I gameroi It was named in 1970 from material found from the Urumaco formation of Venezuela South America Additionally a Pleistocene gavialoid found on Woodlark Island of Papua New Guinea was initially named Gavialis papuensis in 1905 but has since been proposed to be a member of Ikanogavialis 4 although the poor quality of the preserved material makes it difficult to determine 1 Paleobiology editIkanogavialis may have lived in a coastal paleoenvironment along with other gavialids such as Gryposuchus The strata of the Urumaco formation were deposited in both marine and fluvial settings although it is unclear to which portion both genera belong 5 6 Other gavialoids such as Siquisiquesuchus and Piscogavialis are known to have lived in coastal environments and it is likely that extant freshwater gavialoids such as Gavialis may have originated from these coastal forms 7 8 Ikanogavialis also existed with many other crocodilians in Venezuela during the late Miocene including the giant caiman Purussaurus and an extinct species of Melanosuchus 9 Gavialis Ikanogavialis papuensis was similarly fully marine having been found in association with sea turtles and sirenians It represents the youngest fully marine crocodilian to date 10 Phylogeny editA phylogenetic analysis conducted in a 2007 study found Gryposuchinae to include the genera Aktiogavialis Gryposuchus Ikanogavialis Piscogavialis and Siquisiquesuchus Below is a cladogram from the 2007 analysis showing the phylogenetic relationships of gryposuchines among gavialoids 11 Gavialoidea Eothoracosaurus Thoracosaurus Eosuchus Argochampsa Gavialidae Eogavialis Gavialis Gryposuchinae Ikanogavialis Piscogavialis Siquisiquesuchus Gryposuchus Aktiogavialis Alternatively a 2018 tip dating study by Lee amp Yates simultaneously using morphological molecular DNA sequencing and stratigraphic fossil age data indicated that the members of Gryposuchinae may in fact be paraphyletic and rather an evolutionary grade towards Gavialis and the gharial as shown in the cladogram below 12 Gavialidae Gavialis gangeticus Gharial Gavialis bengawanicus Gavialis browni Gryposuchus colombianus Ikanogavialis Gryposuchus pachakamue Piscogavialis Harpacochampsa Toyotamaphimeia Penghusuchus Gavialosuchus Tomistoma lusitanicum Tomistoma schlegelii False gharial GryposuchinaeNotes and references edit a b Rio Jonathan P Mannion Philip D 6 September 2021 Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long standing gharial problem PeerJ 9 e12094 doi 10 7717 peerj 12094 PMC 8428266 PMID 34567843 Langston W Gasparini Z 1997 Crocodilians Gryposuchus and the South American gavials In Kay R F Madden R H Cifelli R L Flynn J J eds Vertebrate Paleontology in the Neotropics The Miocene fauna of La Venta Colombia Washington D C Smithsonian Institution Press pp 113 154 ISBN 1 56098 418 X Sill W D 1970 Nota preliminar sobre un nuevo gavial del Plioceno de Venezuela y una discusion de los gaviales sudamericanos Preliminary note on a new gharial Pliocene of Venezuela and a discussion of the South American gavials Ameghiniana 7 151 159 Martin Jeremy E Buffetaut Eric Naksri Wilailuck Lauprasert Komsorn Claude Julien 18 September 2012 Gavialis from the Pleistocene of Thailand and Its Relevance for Drainage Connections from India to Java PLOS One 7 9 e44541 Bibcode 2012PLoSO 744541M doi 10 1371 journal pone 0044541 PMC 3445548 PMID 23028557 Linares O J 2004 Bioestratigrafia de la fauna de mamiferos de las Formaciones Socorro Urumaco y Codore Mioceno Medio Plioceno Temprano de la region de Urumaco Falcon Venezuela Paleobiologia Neotropical 1 1 26 Sanchez Villagra M R Aguilera O A 2006 Neogene vertebrates from Urumaco Falcon State Venezuela diversity and significance Journal of Systematic Palaeontology 4 3 213 220 doi 10 1017 S1477201906001829 S2CID 84357359 Kraus R 1998 The cranium of Piscogavialis jugaliperforatus n gen n sp Gavialidae Crocodylia from the Miocene of Peru Palaontologische Zeitschrift 72 3 4 389 406 doi 10 1007 BF02988368 S2CID 84214781 Brochu C A Rincon A D 2004 A gavialoid crocodylian from the Lower Miocene of Venezuela Special Papers in Palaeontology 71 61 78 Aguilera O A Driff D Bocquentin Villanueva J 2006 A new giant Purussaurus Crocodyliformes Alligatoridae from the Upper Miocene Urumaco Formation Venezuela Journal of Systematic Palaeontology 4 3 221 232 doi 10 1017 S147720190600188X S2CID 85950121 Molnar R E 1982 A longirostrine crocodilian from Murua Woodlark Solomon Sea Memoirs of the Queensland Museum 20 675 685 Velez Juarbe Jorge Brochu C A Santos H 2007 A gharial from the Oligocene of Puerto Rico transoceanic dispersal in the history of a non marine reptile Proceedings of the Royal Society B 274 1615 1245 1254 doi 10 1098 rspb 2006 0455 PMC 2176176 PMID 17341454 Michael S Y Lee Adam M Yates 27 June 2018 Tip dating and homoplasy reconciling the shallow molecular divergences of modern gharials with their long fossil Proceedings of the Royal Society B 285 1881 doi 10 1098 rspb 2018 1071 PMC 6030529 PMID 30051855 External links editIkanogavialis in the Paleobiology Database nbsp Paleontology portal Retrieved from https en wikipedia org w index php title Ikanogavialis amp oldid 1183372671, wikipedia, wiki, book, books, library,

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