Scleromochlus: Difference between revisions
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'''''Scleromochlus''''' (from {{ |
'''''Scleromochlus''''' (from {{langx|el|σκληρός}} {{transl|el|sklērós}}, 'hard' and {{langx|el|μοχλός}} {{transl|el|mokhlós}}, 'lever') is an [[extinct]] [[genus]] of small [[Pterosauromorpha|pterosauromorph]] [[Archosaur|archosaurs]] from the [[Triassic|Late Triassic]] [[Lossiemouth Sandstone]] of [[Scotland]]. The genus contains the type and only species '''''Scleromochlus taylori''''', named by [[Arthur Smith Woodward]] in 1907.<ref name="woodward1907">{{cite journal | last1 = Woodward | first1 = A.S. | author-link = Arthur Smith Woodward | title = On a New Dinosaurian Reptile (''Scleromochlus Taylori'', gen. Et sp. Nov.) from the Trias of Lossiemouth, Elgin | journal = Quarterly Journal of the Geological Society | volume = 63 | issue = 1–4 | pages= 140–144 | year = 1907 | doi = 10.1144/GSL.JGS.1907.063.01-04.12 | s2cid = 131522263 | url =https://www.biodiversitylibrary.org/item/114069#page/263/mode/1up}}</ref> |
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==Discovery== |
==Discovery== |
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[[File:Scleromochlus lithograph.jpg|thumb|left|upright|[[Lithograph]] of the holotype]] |
[[File:Scleromochlus lithograph.jpg|thumb|left|upright|[[Lithograph]] of the holotype]] |
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Its fossils have been found in the [[Carnian]] [[Lossiemouth Sandstone]] of [[Scotland]]. The [[holotype]] was discovered around 1900 and is listed as specimen BMNH R3556, a partial skeleton preserved as an impression in [[sandstone]], with portions of the skull and tail missing.<ref name="woodward1907"/> |
Its fossils have been found in the [[Carnian]] [[Lossiemouth Sandstone]] of [[Scotland]]. The [[holotype]] was discovered around 1900 and is listed as specimen BMNH R3556, a partial skeleton preserved as an impression in [[sandstone]], with portions of the skull and tail missing.<ref name="woodward1907"/> |
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[[Arthur Smith Woodward]] named and described ''Scleromochlus taylori'' in 1907.<ref name="woodward1907" /> |
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==Description== |
==Description== |
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''Scleromochlus taylori'' was about {{convert|181|mm}} long, with long hind legs; it may have been capable of four-legged and two-legged locomotion. Studies about its gait suggest that it engaged in [[kangaroo]]- or [[springhare]]-like [[plantigrade]] hopping;<ref name=":0">{{Cite journal |last1=Sereno |first1=Paul C. |author-link1=Paul Sereno |last2=Arcucci |first2=Andrea B. |date=1994 |title=Dinosaurian precursors from the Middle Triassic of Argentina: ''Marasuchus lilloensis'', gen. nov. |url=https://www.tandfonline.com/doi/abs/10.1080/02724634.1994.10011538 |url-access=subscription |journal=[[Journal of Vertebrate Paleontology]] |volume=14 |issue=1 |pages=53–73 |doi=10.1080/02724634.1994.10011538 |issn= |
''Scleromochlus taylori'' was about {{convert|181|mm}} long, with long hind legs; it may have been capable of four-legged and two-legged locomotion. Studies about its gait suggest that it engaged in [[kangaroo]]- or [[springhare]]-like [[plantigrade]] hopping;<ref name=":0">{{Cite journal |last1=Sereno |first1=Paul C. |author-link1=Paul Sereno |last2=Arcucci |first2=Andrea B. |date=1994 |title=Dinosaurian precursors from the Middle Triassic of Argentina: ''Marasuchus lilloensis'', gen. nov. |url=https://www.tandfonline.com/doi/abs/10.1080/02724634.1994.10011538 |url-access=subscription |journal=[[Journal of Vertebrate Paleontology]] |volume=14 |issue=1 |pages=53–73 |doi=10.1080/02724634.1994.10011538 |issn=0272-4634}}</ref><ref name="benton1999">{{cite journal | last1=Benton | first1=Michael J. | author-link=Michael J. Benton | title=''Scleromochlus taylori'' and the origin of dinosaurs and pterosaurs| pages= 1423–1446 | year=1999 | volume=354 |pmc=1692658 | journal=Philosophical Transactions of the Royal Society B: Biological Sciences | doi = 10.1098/rstb.1999.0489 | jstor=57034 | issue=1388 }}</ref><ref>{{cite book |last=Witton |first=Mark P. |author-link=Mark P. Witton |title=Pterosaurs: Natural History, Evolution, Anatomy |date=2013 |publisher=Princeton University Press |isbn=9780691150611}}</ref> however, a 2020 reassessment of ''Scleromochlus'' by Bennett suggested that it was a "sprawling quadrupedal hopper analogous to frogs."<ref name="bennett2020">{{cite journal |last=Bennett |first=S. Christopher |year=2020 |title=Reassessment of the Triassic archosauriform ''Scleromochlus taylori'': neither runner nor biped, but hopper |journal=[[PeerJ]] |volume=8 |pages=e8418 |doi=10.7717/peerj.8418|pmid=32117608 |pmc=7035874 |issn=2167-8359|doi-access=free}}</ref> If ''Scleromochlus'' is indeed related to [[pterosaurs]], this may offer insight as to how the latter evolved, since early pterosaurs also show adaptations for saltatorial locomotion.<ref>{{cite journal |last=Witton |first=Mark P. |date=2015 |title=Were early pterosaurs inept terrestrial locomotors? |journal=PeerJ |volume=3 |pages=e1018 |doi=10.7717/peerj.1018|pmid=26157605 |pmc=4476129 |issn=2167-8359 |doi-access=free }}</ref> |
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==Classification== |
==Classification== |
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[[File:Scleromochlus skeletal.png|thumb|Skeletal reconstruction as a basal archosauriform (from Bennett, 2020)]] |
[[File:Scleromochlus skeletal.png|thumb|Skeletal reconstruction as a basal archosauriform (from Bennett, 2020)]] |
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[[File:Scleromochlus restoration.jpg|thumb|left|Life restoration of ''Scleromochlus'' as a lagerpetid-like pterosauromorph (following Foffa, 2022)]] |
[[File:Scleromochlus restoration.jpg|thumb|left|Life restoration of ''Scleromochlus'' as a lagerpetid-like pterosauromorph (following Foffa, 2022)]] |
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A lightly built [[cursorial]] animal, its [[phylogeny|phylogenetic]] position has been debated; as different analyses have found it to be either the [[basal (phylogenetics)|basal]]-most [[ornithodira]]n, the sister-taxon to [[Pterosauria]], or a basal member of [[Avemetatarsalia]] that lies outside of [[Ornithodira]]. In the phylogenetic analyses conducted by Nesbitt ''et al.'' (2017) ''Scleromochlus'' was recovered either as a basal member of [[Dinosauromorpha]] or as a non-[[aphanosauria]]n, non-pterosaur basal avemetatarsalian. However, the authors stressed that scoring ''Scleromochlus'' was challenging given the small size and poor preservation of the fossils, and stated that it could not be scored for many of the important characters that optimize near the base of Avemetatarsalia.<ref name="nesbitt2017">{{cite journal |first1=S.J. |last1=Nesbitt |first2=R.J. |last2=Butler |first3=M.D. |last3=Ezcurra |first4=P.M. |last4=Barrett |first5=M.R. |last5=Stocker |first6=K.D. |last6=Angielczyk |first7=R.M.H. |last7=Smith |first8=C.A. |last8=Sidor |first9=G. |last9=Niedźwiedzki |first10=A.G. |last10=Sennikov |first11=A.J. |last11=Charig |year=2017 |title=The earliest bird-line archosaurs and the assembly of the dinosaur body plan |journal=Nature |volume=544 |issue=7651 |pages=484–487 |doi=10.1038/nature22037 |url-access=subscription |url=https://www.nature.com/articles/nature22037 |pmid=28405026|bibcode=2017Natur.544..484N }}</ref> |
A lightly built [[cursorial]] animal, its [[phylogeny|phylogenetic]] position has been debated; as different analyses have found it to be either the [[basal (phylogenetics)|basal]]-most [[ornithodira]]n, the sister-taxon to [[Pterosauria]], or a basal member of [[Avemetatarsalia]] that lies outside of [[Ornithodira]]. In the phylogenetic analyses conducted by Nesbitt ''et al.'' (2017) ''Scleromochlus'' was recovered either as a basal member of [[Dinosauromorpha]] or as a non-[[aphanosauria]]n, non-pterosaur basal avemetatarsalian. However, the authors stressed that scoring ''Scleromochlus'' was challenging given the small size and poor preservation of the fossils, and stated that it could not be scored for many of the important characters that optimize near the base of Avemetatarsalia.<ref name="nesbitt2017">{{cite journal |first1=S.J. |last1=Nesbitt |first2=R.J. |last2=Butler |first3=M.D. |last3=Ezcurra |first4=P.M. |last4=Barrett |first5=M.R. |last5=Stocker |first6=K.D. |last6=Angielczyk |first7=R.M.H. |last7=Smith |first8=C.A. |last8=Sidor |first9=G. |last9=Niedźwiedzki |first10=A.G. |last10=Sennikov |first11=A.J. |last11=Charig |year=2017 |title=The earliest bird-line archosaurs and the assembly of the dinosaur body plan |journal=Nature |volume=544 |issue=7651 |pages=484–487 |doi=10.1038/nature22037 |url-access=subscription |url=https://www.nature.com/articles/nature22037 |pmid=28405026|bibcode=2017Natur.544..484N |hdl=11336/49585 |hdl-access=free }}</ref> |
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In 2020, Bennett interpreted ''Scleromochlus'' as possessing certain characteristics, including [[osteoderm]]s and a [[crurotarsal]] morphology of the ankle, which suggested that ''Scleromochlus'' was not closely related to ornithodirans. Instead, he argued for a position of ''Scleromochlus'' among the [[Doswelliidae]] or elsewhere among [[basal (phylogenetics)|basal]] members of the [[Archosauriformes]].<ref name="bennett2020"/> |
In 2020, Bennett interpreted ''Scleromochlus'' as possessing certain characteristics, including [[osteoderm]]s and a [[crurotarsal]] morphology of the ankle, which suggested that ''Scleromochlus'' was not closely related to ornithodirans. Instead, he argued for a position of ''Scleromochlus'' among the [[Doswelliidae]] or elsewhere among [[basal (phylogenetics)|basal]] members of the [[Archosauriformes]].<ref name="bennett2020"/> |
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However, in 2022, Foffa and colleagues reconstructed a complete skeleton using [[X-ray microtomography|microcomputed tomographic]] scans of the |
However, in 2022, Foffa and colleagues reconstructed a complete skeleton using [[X-ray microtomography|microcomputed tomographic]] scans of the seven specimens found to date. This enabled a new phylogenetic analysis to be undertaken, which strongly supported the hypothesis that ''Scleromochlus'' was a member of the [[Pterosauromorpha]] – either as a genus of the [[Lagerpetidae]] family (shown to be a part of Pterosauromorpha in 2020<ref>{{cite journal |last1=Ezcurra |first1=Martín D |author-link1=Martin Ezcurra |last2=Nesbitt |first2=Sterling J. |last3=Bronzati |first3=Mario |last4=Dalla Vecchia |first4=Fabio Marco |last5=Agnolin |first5=Federico L. |last6=Benson |first6=Roger B. J. |last7=Brissón Egli |first7=Federico |last8=Cabreira |first8=Sergio F. |last9=Evers |first9=Serjoscha W. |last10=Gentil |first10=Adriel R. |last11=Irmis |first11=Randall B. |last12=Martinelli |first12=Agustín G. |last13=Novas |first13=Fernando E. |last14=Roberto da Silva |first14=Lúcio |last15=Smith |first15=Nathan D. |last16=Stocker |first16=Michelle R. |last17=Turner |first17=Alan H. |last18=Langer |first18=Max C. |date=2020 |title=Enigmatic dinosaur precursors bridge the gap to the origin of Pterosauria |url=https://www.nature.com/articles/s41586-020-3011-4 |url-access=subscription |journal=Nature |volume=588 |issue=7838 |pages=445–449 |doi=10.1038/s41586-020-3011-4 |issn=1476-4687 |access-date=6 October 2022}}</ref>) or as the [[sister group]] to pterosaurs and lagerpetids. Previous alternative classifications were demonstrated to have been based on misinterpretations of incomplete or ambiguous anatomical features found in the fossil record.<ref>{{cite journal |last1=Foffa |first1=Davide |last2=Dunne |first2=Emma M. |last3=Nesbitt |first3=Sterling J. |author-link3=Sterling Nesbitt |last4=Butler |first4=Richard J. |author-link4=Richard J. Butler |last5=Fraser |first5=Nicholas C. |author-link5=Nicholas Fraser |last6=Brusatte |first6=Stephen L. |author-link6=Stephen L. Brusatte |last7=Farnsworth |first7=Alexander |last8=Lunt |first8=Daniel J. |last9=Valdes |first9=Paul J. |last10=Walsh |first10=Stig |last11=Barrett |first11=Paul M. |date=2022 |title=''Scleromochlus'' and the early evolution of Pterosauromorpha |url=https://www.nature.com/articles/s41586-022-05284-x |url-access=subscription |journal=Nature |volume=610 |issue=7931 |pages=313–318 |doi=10.1038/s41586-022-05284-x|hdl=20.500.11820/3134b3f1-41e0-47bb-9688-a5e5b0b64492 |hdl-access=free }}</ref><ref>{{cite web |last=Gill |first=Victoria |date=6 October 2022 |title=Scottish fossil revealed to be pterodactyl ancestor |url=https://www.bbc.co.uk/news/science-environment-63146271 |website=BBC News |publisher=[[BBC]] |access-date=6 October 2022}}</ref> |
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== References == |
== References == |
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Latest revision as of 09:36, 23 October 2024
| Scleromochlus Temporal range: Late Triassic,
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|---|---|
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| Cast of holotype specimen NHMUK R3556 | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Ornithodira |
| Clade: | †Pterosauromorpha |
| Family: | †Scleromochlidae Huene, 1914 |
| Genus: | †Scleromochlus Woodward, 1907 |
| Species: | †S. taylori
|
| Binomial name | |
| †Scleromochlus taylori Woodward, 1907
| |
Scleromochlus (from Greek: σκληρός sklērós, 'hard' and Greek: μοχλός mokhlós, 'lever') is an extinct genus of small pterosauromorph archosaurs from the Late Triassic Lossiemouth Sandstone of Scotland. The genus contains the type and only species Scleromochlus taylori, named by Arthur Smith Woodward in 1907.[1]
Discovery
[edit]
Its fossils have been found in the Carnian Lossiemouth Sandstone of Scotland. The holotype was discovered around 1900 and is listed as specimen BMNH R3556, a partial skeleton preserved as an impression in sandstone, with portions of the skull and tail missing.[1]
Arthur Smith Woodward named and described Scleromochlus taylori in 1907.[1]
Description
[edit]Scleromochlus taylori was about 181 millimetres (7.1 in) long, with long hind legs; it may have been capable of four-legged and two-legged locomotion. Studies about its gait suggest that it engaged in kangaroo- or springhare-like plantigrade hopping;[2][3][4] however, a 2020 reassessment of Scleromochlus by Bennett suggested that it was a "sprawling quadrupedal hopper analogous to frogs."[5] If Scleromochlus is indeed related to pterosaurs, this may offer insight as to how the latter evolved, since early pterosaurs also show adaptations for saltatorial locomotion.[6]
Classification
[edit]
A lightly built cursorial animal, its phylogenetic position has been debated; as different analyses have found it to be either the basal-most ornithodiran, the sister-taxon to Pterosauria, or a basal member of Avemetatarsalia that lies outside of Ornithodira. In the phylogenetic analyses conducted by Nesbitt et al. (2017) Scleromochlus was recovered either as a basal member of Dinosauromorpha or as a non-aphanosaurian, non-pterosaur basal avemetatarsalian. However, the authors stressed that scoring Scleromochlus was challenging given the small size and poor preservation of the fossils, and stated that it could not be scored for many of the important characters that optimize near the base of Avemetatarsalia.[7]
In 2020, Bennett interpreted Scleromochlus as possessing certain characteristics, including osteoderms and a crurotarsal morphology of the ankle, which suggested that Scleromochlus was not closely related to ornithodirans. Instead, he argued for a position of Scleromochlus among the Doswelliidae or elsewhere among basal members of the Archosauriformes.[5]
However, in 2022, Foffa and colleagues reconstructed a complete skeleton using microcomputed tomographic scans of the seven specimens found to date. This enabled a new phylogenetic analysis to be undertaken, which strongly supported the hypothesis that Scleromochlus was a member of the Pterosauromorpha – either as a genus of the Lagerpetidae family (shown to be a part of Pterosauromorpha in 2020[8]) or as the sister group to pterosaurs and lagerpetids. Previous alternative classifications were demonstrated to have been based on misinterpretations of incomplete or ambiguous anatomical features found in the fossil record.[9][10]
References
[edit]- ^ a b c Woodward, A.S. (1907). "On a New Dinosaurian Reptile (Scleromochlus Taylori, gen. Et sp. Nov.) from the Trias of Lossiemouth, Elgin". Quarterly Journal of the Geological Society. 63 (1–4): 140–144. doi:10.1144/GSL.JGS.1907.063.01-04.12. S2CID 131522263.
- ^ Sereno, Paul C.; Arcucci, Andrea B. (1994). "Dinosaurian precursors from the Middle Triassic of Argentina: Marasuchus lilloensis, gen. nov". Journal of Vertebrate Paleontology. 14 (1): 53–73. doi:10.1080/02724634.1994.10011538. ISSN 0272-4634.
- ^ Benton, Michael J. (1999). "Scleromochlus taylori and the origin of dinosaurs and pterosaurs". Philosophical Transactions of the Royal Society B: Biological Sciences. 354 (1388): 1423–1446. doi:10.1098/rstb.1999.0489. JSTOR 57034. PMC 1692658.
- ^ Witton, Mark P. (2013). Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press. ISBN 9780691150611.
- ^ a b Bennett, S. Christopher (2020). "Reassessment of the Triassic archosauriform Scleromochlus taylori: neither runner nor biped, but hopper". PeerJ. 8: e8418. doi:10.7717/peerj.8418. ISSN 2167-8359. PMC 7035874. PMID 32117608.
- ^ Witton, Mark P. (2015). "Were early pterosaurs inept terrestrial locomotors?". PeerJ. 3: e1018. doi:10.7717/peerj.1018. ISSN 2167-8359. PMC 4476129. PMID 26157605.
- ^ Nesbitt, S.J.; Butler, R.J.; Ezcurra, M.D.; Barrett, P.M.; Stocker, M.R.; Angielczyk, K.D.; Smith, R.M.H.; Sidor, C.A.; Niedźwiedzki, G.; Sennikov, A.G.; Charig, A.J. (2017). "The earliest bird-line archosaurs and the assembly of the dinosaur body plan". Nature. 544 (7651): 484–487. Bibcode:2017Natur.544..484N. doi:10.1038/nature22037. hdl:11336/49585. PMID 28405026.
- ^ Ezcurra, Martín D; Nesbitt, Sterling J.; Bronzati, Mario; Dalla Vecchia, Fabio Marco; Agnolin, Federico L.; Benson, Roger B. J.; Brissón Egli, Federico; Cabreira, Sergio F.; Evers, Serjoscha W.; Gentil, Adriel R.; Irmis, Randall B.; Martinelli, Agustín G.; Novas, Fernando E.; Roberto da Silva, Lúcio; Smith, Nathan D.; Stocker, Michelle R.; Turner, Alan H.; Langer, Max C. (2020). "Enigmatic dinosaur precursors bridge the gap to the origin of Pterosauria". Nature. 588 (7838): 445–449. doi:10.1038/s41586-020-3011-4. ISSN 1476-4687. Retrieved 6 October 2022.
- ^ Foffa, Davide; Dunne, Emma M.; Nesbitt, Sterling J.; Butler, Richard J.; Fraser, Nicholas C.; Brusatte, Stephen L.; Farnsworth, Alexander; Lunt, Daniel J.; Valdes, Paul J.; Walsh, Stig; Barrett, Paul M. (2022). "Scleromochlus and the early evolution of Pterosauromorpha". Nature. 610 (7931): 313–318. doi:10.1038/s41586-022-05284-x. hdl:20.500.11820/3134b3f1-41e0-47bb-9688-a5e5b0b64492.
- ^ Gill, Victoria (6 October 2022). "Scottish fossil revealed to be pterodactyl ancestor". BBC News. BBC. Retrieved 6 October 2022.
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