A neural spine sail is a large, flattish protrusion from the back of an animal formed of a sequence of extended vertebral spinous processes and associated tissues. Such structures are comparatively rare in modern animals, but have been identified in many extinctspecies of amphibians and amniotes. Paleontologists have proposed a number of ways in which the sail could have functioned in life.
Varying suggestions have been made for the function of the sail.
Thermoregulation
The structure may have been used for thermoregulation. The base of the spines have a channel which may have contained a blood vessel supplying abundant blood to the sail. The animal could have used the sail's large surface area to absorb heat from the sun in the morning. As ectotherms they required heat from an external source before their muscles would start to function properly. A predator would thus have an advantage over its slower moving prey. The sail could be used in reverse if the animal was overheating. By standing in the shade, the sail would radiate heat outwards.[1]
However, recent studies have put in doubt the efficiency of this purported means of thermoregulation, and indeed no extinct sailed animal is currently assumed to have used its sails for thermoregulation.[2][3]
Sexual selection
Elaborate body structures of many modern-day animals usually serve to attract members of the opposite sex during mating. This has been proposed as one potential function of the sail.[1]
Food storage
The tall neural spines of a bison form a hump rather than a sail.
The structure may also have been more hump-like than sail-like, as noted by Stromer in 1915 ("one might rather think of the existence of a large hump of fat [German: Fettbuckel], to which the [neural spines] gave internal support")[4] and by Jack Bowman Bailey in 1997.[5] In support of his "buffalo-back" hypothesis, Bailey argued that in Spinosaurus, Ouranosaurus, and other dinosaurs with long neural spines, the spines were relatively shorter and thicker than the spines of pelycosaurs (which were known to have sails); instead, the dinosaurs' neural spines were similar to the neural spines of extinct hump-backed mammals such as Megacerops and Bison latifrons.[5]
Camouflage
Dimetrodon may have used the sail on its back to help camouflage itself when hiding among reeds and waiting to ambush its prey.[6]
Sound display
Gregory Paul argued that parallel neck sails of Amargasaurus would have reduced neck flexion. Instead, he proposed that, with their circular rather than flat cross-sections, these spines were more likely covered with a horny sheath. He also suggests that they could have been clattered together for a sound display.[7] In 2022, a detailed study was published by Cerda et al. analyzing the structure, morphology, and microanatomy of the vertebral spines of Amargasaurus. They suggested that the spines were not covered in a keratinous sheath as previously believed. Osteohistology of the spines suggests that they were likely, if not exclusively, covered in a sail of skin. The spines are also highly vascularized and bear cyclical growth marks, adding credence to this theory.[8]
^ abD.R. Khanna, Biology of Reptiles, pp. 59-60, Discovery Publishing House, 2004 ISBN8171419070.
^Tomkins, Joseph L.; LeBas, Natasha R.; Witton, Mark P.; Martill, David M. & Humphries, Stuart (2010). "Positive allometry and the prehistory of sexual selection" (PDF). American Naturalist. 176 (2): 141–148. doi:10.1086/653001. PMID 20565262. S2CID 36207.
^Huttenlocker, A. K.; Mazierski, D. & Reisz, R. R. (2011). "Comparative osteohistology of hyperelongate neural spines in the Edaphosauridae (Amniota: Synapsida)". Palaeontology. 54 (3): 573–590. doi:10.1111/j.1475-4983.2011.01047.x.
^Stromer, E. (1915). "Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltier-Reste der Baharije-Stufe (unterstes Cenoman). 3. Das Original des Theropoden Spinosaurus aegyptiacus nov. gen., nov. spec". Abhandlungen der Königlich Bayerischen Akademie der Wissenschaften, Mathematisch-physikalische Klasse (in German). 28 (3): 1–32.
^ abBailey, J.B. (1997). "Neural spine elongation in dinosaurs: sailbacks or buffalo-backs?". Journal of Paleontology. 71 (6): 1124–1146. doi:10.1017/S0022336000036076. JSTOR 1306608.
^Bramwell, C. D. & Fellgett, P. B. (16 February 1973). "Thermal regulation in sail lizards". Nature. 242 (5394): 203–205. Bibcode:1973Natur.242..203B. doi:10.1038/242203a0. ISSN 0028-0836. S2CID 4159825. Many suggestions have been made about the function of the sail, as camouflage among reeds while it waited for prey, for sexual display, or literally as a sail while swimming
^Paul, Gregory S. (2000) The Scientific American Book of Dinosaurs, p 94. St. Martin's Press. ISBN0-312-26226-4.
^Cerda, Ignacio A.; Novas, Fernando E.; Carballido, José Luis; Salgado, Leonardo (2022-03-24). "Osteohistology of the hyperelongate hemispinous processes of Amargasaurus cazaui (Dinosauria: Sauropoda): Implications for soft tissue reconstruction and functional significance". Journal of Anatomy: joa.13659. doi:10.1111/joa.13659. ISSN 0021-8782. PMID 35332552. S2CID 247677750.
February 18, 2023
neural, spine, sail, neural, spine, sail, large, flattish, protrusion, from, back, animal, formed, sequence, extended, vertebral, spinous, processes, associated, tissues, such, structures, comparatively, rare, modern, animals, have, been, identified, many, ext. A neural spine sail is a large flattish protrusion from the back of an animal formed of a sequence of extended vertebral spinous processes and associated tissues Such structures are comparatively rare in modern animals but have been identified in many extinct species of amphibians and amniotes Paleontologists have proposed a number of ways in which the sail could have functioned in life Mounted skeleton of Dimetrodon limbatus Contents 1 Function 1 1 Thermoregulation 1 2 Sexual selection 1 3 Food storage 1 4 Camouflage 1 5 Sound display 2 List of organisms with a sail 2 1 Amphibians 2 2 Amniotes 3 ReferencesFunction Edit Crested chameleon an extant reptile with a sail on its back Varying suggestions have been made for the function of the sail Thermoregulation Edit The structure may have been used for thermoregulation The base of the spines have a channel which may have contained a blood vessel supplying abundant blood to the sail The animal could have used the sail s large surface area to absorb heat from the sun in the morning As ectotherms they required heat from an external source before their muscles would start to function properly A predator would thus have an advantage over its slower moving prey The sail could be used in reverse if the animal was overheating By standing in the shade the sail would radiate heat outwards 1 However recent studies have put in doubt the efficiency of this purported means of thermoregulation and indeed no extinct sailed animal is currently assumed to have used its sails for thermoregulation 2 3 Sexual selection Edit Elaborate body structures of many modern day animals usually serve to attract members of the opposite sex during mating This has been proposed as one potential function of the sail 1 Food storage Edit The tall neural spines of a bison form a hump rather than a sail The structure may also have been more hump like than sail like as noted by Stromer in 1915 one might rather think of the existence of a large hump of fat German Fettbuckel to which the neural spines gave internal support 4 and by Jack Bowman Bailey in 1997 5 In support of his buffalo back hypothesis Bailey argued that in Spinosaurus Ouranosaurus and other dinosaurs with long neural spines the spines were relatively shorter and thicker than the spines of pelycosaurs which were known to have sails instead the dinosaurs neural spines were similar to the neural spines of extinct hump backed mammals such as Megacerops and Bison latifrons 5 Camouflage Edit Dimetrodon may have used the sail on its back to help camouflage itself when hiding among reeds and waiting to ambush its prey 6 Sound display Edit Gregory Paul argued that parallel neck sails of Amargasaurus would have reduced neck flexion Instead he proposed that with their circular rather than flat cross sections these spines were more likely covered with a horny sheath He also suggests that they could have been clattered together for a sound display 7 In 2022 a detailed study was published by Cerda et al analyzing the structure morphology and microanatomy of the vertebral spines of Amargasaurus They suggested that the spines were not covered in a keratinous sheath as previously believed Osteohistology of the spines suggests that they were likely if not exclusively covered in a sail of skin The spines are also highly vascularized and bear cyclical growth marks adding credence to this theory 8 List of organisms with a sail Edit Spinosaurus a dinosaur with a sail Amphibians Edit PlatyhystrixAmniotes Edit Many Synapsids Edaphosaurids Sphenacodontids Many Poposauroids Ctenosauriscids Lotosaurids Certain dinosaurs Acrocanthosaurus Amargasaurus Bajadasaurus Deinocheirus Ichthyovenator Ouranosaurus Pilmatueia Rebbachisaurus Spinosaurus Suchomimus OxalaiaReferences Edit a b D R Khanna Biology of Reptiles pp 59 60 Discovery Publishing House 2004 ISBN 8171419070 Tomkins Joseph L LeBas Natasha R Witton Mark P Martill David M amp Humphries Stuart 2010 Positive allometry and the prehistory of sexual selection PDF American Naturalist 176 2 141 148 doi 10 1086 653001 PMID 20565262 S2CID 36207 Huttenlocker A K Mazierski D amp Reisz R R 2011 Comparative osteohistology of hyperelongate neural spines in the Edaphosauridae Amniota Synapsida Palaeontology 54 3 573 590 doi 10 1111 j 1475 4983 2011 01047 x Stromer E 1915 Ergebnisse der Forschungsreisen Prof E Stromers in den Wusten Agyptens II Wirbeltier Reste der Baharije Stufe unterstes Cenoman 3 Das Original des Theropoden Spinosaurus aegyptiacus nov gen nov spec Abhandlungen der Koniglich Bayerischen Akademie der Wissenschaften Mathematisch physikalische Klasse in German 28 3 1 32 a b Bailey J B 1997 Neural spine elongation in dinosaurs sailbacks or buffalo backs Journal of Paleontology 71 6 1124 1146 doi 10 1017 S0022336000036076 JSTOR 1306608 Bramwell C D amp Fellgett P B 16 February 1973 Thermal regulation in sail lizards Nature 242 5394 203 205 Bibcode 1973Natur 242 203B doi 10 1038 242203a0 ISSN 0028 0836 S2CID 4159825 Many suggestions have been made about the function of the sail as camouflage among reeds while it waited for prey for sexual display or literally as a sail while swimming Paul Gregory S 2000 The Scientific American Book of Dinosaurs p 94 St Martin s Press ISBN 0 312 26226 4 Cerda Ignacio A Novas Fernando E Carballido Jose Luis Salgado Leonardo 2022 03 24 Osteohistology of the hyperelongate hemispinous processes of Amargasaurus cazaui Dinosauria Sauropoda Implications for soft tissue reconstruction and functional significance Journal of Anatomy joa 13659 doi 10 1111 joa 13659 ISSN 0021 8782 PMID 35332552 S2CID 247677750 Retrieved from https en wikipedia org w index php title Neural spine sail amp oldid 1135932412, wikipedia, wiki, book, books, library,
