Heterodontosaurus: Difference between revisions
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*[[extinction|†]]'''''H. tucki''''' <small>Crompton & Charig, 1962 ([[type species|type]])</small> |
*[[extinction|†]]'''''H. tucki''''' <small>Crompton & Charig, 1962 ([[type species|type]])</small> |
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'''''Heterodontosaurus''''' (meaning "different toothed lizard") is a [[genus]] of small herbivorous [[dinosaur]] with prominent canine teeth which lived in the [[Early Jurassic]] of [[South Africa]]. It was similar to a [[hypsilophodont]] in shape, and ate plants, despite its canines.<ref name="Benton, Michael J, Prehistoric Life" |
'''''Heterodontosaurus''''' (meaning "different toothed lizard") is a [[genus]] of small herbivorous [[dinosaur]] with prominent canine teeth which lived in the [[Early Jurassic]] of [[South Africa]]. It was similar to a [[hypsilophodont]] in shape, and ate plants, despite its canines.<ref name="Benton, Michael J, Prehistoric Life"/> |
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==Description== |
==Description== |
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[[File:Human-heterodontosaurus size comparison.png|thumb|left|Size compared to a human]] |
[[File:Human-heterodontosaurus size comparison.png|thumb|left|Size compared to a human]] |
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''Heterodontosaurus'' was a small, fleetfooted ornithischian classified inside the family [[Heterodontosauridae]]. The family contains some of the smallest known ornithischians<ref name="dinosauria1990" /> – the North American ''[[Fruitadens]]'', for example, reached a length of only 65 to 75 cm.<ref name="butleretal2010" /> ''Heterodontosaurus'' was amongst the largest known members of its family, reaching a length of between 1 to 1.75 m and weighing 1.8 or 10 kg.<ref name="butler2012" /> Only the South African ''[[Lycorhinus]]'' might have been larger.<ref name="gow1990" /><ref name="sereno161" /> |
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The skull was robustly build and triangular in side view. The front of the jaws where covered by a toothless [[keratin|horny]] beak. The upper beak was carried by the [[premaxilla]] and the lower beak by the [[predentary]], which in ornithischians are the foremost bones of the upper and lower jaw, respectively. The eye openings were proportionally large and almost circular in shape, while the [[external naris|external nostril openings were small. A large spur-like bone, the [[palpebral (bone)|palpebral]], protruded backwards into the eye opening.<ref name="normanetal2011"/> Below the eye socket, the [[jugal bone]] gave rise to a sidewards projecting horn like process. The antorbital fossa, a large depression between the eye and nostril openings, contained two smaller openings.<ref name="dinosauria1990" /> Ventrally, the antorbital fossa was bounded by a prominent bony ridge, to which the animal's fleshy cheek would have been attached. Behind the eye opening, there was the proportionally large [[Skull#Temporal fenestrae|lower temporal fenestra]], which in ''Heterodontosaurus'' was egg-shaped and tilted back. The elliptical [[Skull#Temporal fenestrae|upper tempral fenestra]] was visible only in top view of the skull. The left and right upper temporal fenestrae were separated by a pronounced [[sagittal crest]], which in the living animal would have provided attachment sides for the jaw musculature.<ref name="normanetal2011"/> |
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| ⚫ | More unusual was that the hand of ''Heterodontosaurus'' had five fingers, two of which seem to be opposable. This configuration allowed ''Heterodontosaurus'' to grasp and manipulate food. The bone in the foot and ankle were fused in a manner reminiscent of those in birds.<ref name="Benton, Michael J, Prehistoric Life" /><ref name="ageofdinosaursheterodontosaurus"/><ref>https://archive.org/stream/annalsofsouth79197980sout/#page/159/mode/1up</ref> |
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| ⚫ | It had a long, narrow [[pelvis]] and a [[pubis (bone)|pubis]] which resembled those possessed by more advanced [[ornithischian]]s.<ref name="Benton, Michael J, Prehistoric Life" /><ref name="ageofdinosaursheterodontosaurus"/><ref name="normanetal2011"/> More unusual was that the hand of ''Heterodontosaurus'' had five fingers, two of which seem to be opposable. This configuration allowed ''Heterodontosaurus'' to grasp and manipulate food. The bone in the foot and ankle were fused in a manner reminiscent of those in birds.<ref name="Benton, Michael J, Prehistoric Life" /><ref name="ageofdinosaursheterodontosaurus"/><ref>https://archive.org/stream/annalsofsouth79197980sout/#page/159/mode/1up</ref> |
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===Dentition=== |
===Dentition=== |
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==References== |
==References== |
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{{Reflist|2 |
{{Reflist|2|refs= |
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<ref name="Benton, Michael J, Prehistoric Life">{{cite book|last=Benton|first=Michael J.|title=Prehistoric Life|year=2012|publisher=Dorling Kindersley|location=Edinburgh, Scotland|isbn=978-0-7566-9910-9|page='''271'''}}</ref> |
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| ⚫ | <ref name="normanetal2011">{{Cite journal|doi=10.1111/j.1096-3642.2011.00697.x|title=The Lower Jurassic ornithischian dinosaur ''Heterodontosaurus tucki'' Crompton & Charig, 1962: Cranial anatomy, functional morphology, taxonomy, and relationships|journal=Zoological Journal of the Linnean Society|pages=no|year=2011|last1=Norman|first1=D. B.|last2=Crompton|first2=A. W.|last3=Butler|first3=R. J.|last4=Porro|first4=L. B.|last5=Charig|first5=A. J.}}</ref> |
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<ref name="dinosauria1990">{{cite book| first=D.B. |last=Weishampel |coauthors=L.M. Witmer |chapter=Heterodontosauridae | editor=D.B. Weishampel, P. Dodson, H. Osmólska |title=The Dinosauria |publisher=University of California Press |year=1990 |ISBN=0-520-06726-6|pages=486–497}}</ref> |
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<ref name="butleretal2010">{{cite journal|author=R.J. Butler, P.M. Galton, L.B. Porro, L.M. Chiappe, D.M. Henderson, G.M. Erickson |title=Lower limits of ornithischian dinosaur body size inferred from a new Upper Jurassic heterodontosaurid from North America |journal=Proceedings of the Royal Society. Series B: Biological Sciences |volume=277 |number=1680 |year=2010 |ISSN=0080-4649 |pages=375–381| DOI=10.1098/rspb.2009.1494}}</ref> |
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<ref name="butler2012>{{Cite journal | last1 = Butler | first1 = R. J. | last2 = Porro | first2 = L. B. | last3 = Galton | first3 = P. M. | last4 = Chiappe | first4 = L. M. | editor1-last = Farke | editor1-first = Andrew A | title = Anatomy and Cranial Functional Morphology of the Small-Bodied Dinosaur Fruitadens haagarorum from the Upper Jurassic of the USA | doi = 10.1371/journal.pone.0031556 | journal = PLoS ONE | volume = 7 | issue = 4 | pages = e31556 | year = 2012 | pmid = 22509242| pmc = 3324477}}</ref> |
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<ref name="gow1990">{{cite journal|authors=C.E. Gow | title=A tooth-bearing maxilla referable to ''Lycorhinus angustidens'' Haughton, 1924 (Dinosauria, Ornithischia) |journal=Annals of the South African Museum| volume=99 |number=10 |year=1990| pages=367–380 |url=[http://biostor.org/reference/110304 Digitalisat]}}</ref> |
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==Sources== |
==Sources== |
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Revision as of 21:41, 19 October 2015
| Heterodontosaurus Temporal range: Early Jurassic,
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| Cast of SAM-PK-K1332, University of California Museum of Paleontology | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Family: | †Heterodontosauridae |
| Subfamily: | †Heterodontosaurinae |
| Genus: | †Heterodontosaurus Crompton & Charig, 1962 |
| Species | |
Heterodontosaurus (meaning "different toothed lizard") is a genus of small herbivorous dinosaur with prominent canine teeth which lived in the Early Jurassic of South Africa. It was similar to a hypsilophodont in shape, and ate plants, despite its canines.[1]
Description
Heterodontosaurus was a small, fleetfooted ornithischian classified inside the family Heterodontosauridae. The family contains some of the smallest known ornithischians[2] – the North American Fruitadens, for example, reached a length of only 65 to 75 cm.[3] Heterodontosaurus was amongst the largest known members of its family, reaching a length of between 1 to 1.75 m and weighing 1.8 or 10 kg.[4] Only the South African Lycorhinus might have been larger.[5][6]
The skull was robustly build and triangular in side view. The front of the jaws where covered by a toothless horny beak. The upper beak was carried by the premaxilla and the lower beak by the predentary, which in ornithischians are the foremost bones of the upper and lower jaw, respectively. The eye openings were proportionally large and almost circular in shape, while the [[external naris|external nostril openings were small. A large spur-like bone, the palpebral, protruded backwards into the eye opening.[7] Below the eye socket, the jugal bone gave rise to a sidewards projecting horn like process. The antorbital fossa, a large depression between the eye and nostril openings, contained two smaller openings.[2] Ventrally, the antorbital fossa was bounded by a prominent bony ridge, to which the animal's fleshy cheek would have been attached. Behind the eye opening, there was the proportionally large lower temporal fenestra, which in Heterodontosaurus was egg-shaped and tilted back. The elliptical upper tempral fenestra was visible only in top view of the skull. The left and right upper temporal fenestrae were separated by a pronounced sagittal crest, which in the living animal would have provided attachment sides for the jaw musculature.[7]
It had a long, narrow pelvis and a pubis which resembled those possessed by more advanced ornithischians.[1][8][7] More unusual was that the hand of Heterodontosaurus had five fingers, two of which seem to be opposable. This configuration allowed Heterodontosaurus to grasp and manipulate food. The bone in the foot and ankle were fused in a manner reminiscent of those in birds.[1][8][9]
Dentition
Another feature is the specialization of teeth which gave rise to the animal's name. Most dinosaurs (and indeed most reptiles) have a single type of tooth in their jaws, while Heterodontosaurus had three. At the front of the jaw beside the beak were small teeth likely used for chopping off leaves and stems.[1][8]
Next in the jaw was a large pair of tusks whose purpose is unknown, but it is speculated that they were used as sexual displays (where the tusks could have been used as weapons by rival males in disputes over mates and territories) or to break open prehistoric termite mounds. The final type of teeth were tall and squared off. This type of teeth was well adapted for chewing. Fleshy cheeks helped keep the food in the mouth while chewing occurred.[1][8] Chewing is relatively common in dinosaurs, but uncommon for other groups of reptiles.[10][11]
This bizarre suite of teeth has led to debate over what heterodontosaurs ate. Some scientists think heterodontosaurs were omnivores who used their differently-shaped teeth to eat both plants and small animals.[1][12]
Discovery
Heterodontosaurus is currently known from specimens of the SAFM (South African Museum) from South Africa.[13] There are two known morphologies of this genus, the second of which is thought by some to represent a different species. The type species, H. tucki, is from the Upper Elliot Formation of the Hettangian age, around 199-196 million years ago.[14]
Classification
The cladogram below follows the analysis by Butler et al., 2011:[15]
| Heterodontosauridae |
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References
- ^ a b c d e f Benton, Michael J. (2012). Prehistoric Life. Edinburgh, Scotland: Dorling Kindersley. p. 271. ISBN 978-0-7566-9910-9.
- ^ a b Weishampel, D.B. (1990). "Heterodontosauridae". In D.B. Weishampel, P. Dodson, H. Osmólska (ed.). The Dinosauria. University of California Press. pp. 486–497. ISBN 0-520-06726-6.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help)CS1 maint: multiple names: editors list (link) - ^ R.J. Butler, P.M. Galton, L.B. Porro, L.M. Chiappe, D.M. Henderson, G.M. Erickson (2010). "Lower limits of ornithischian dinosaur body size inferred from a new Upper Jurassic heterodontosaurid from North America". Proceedings of the Royal Society. Series B: Biological Sciences. 277 (1680): 375–381. doi:10.1098/rspb.2009.1494. ISSN 0080-4649.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Butler, R. J.; Porro, L. B.; Galton, P. M.; Chiappe, L. M. (2012). Farke, Andrew A (ed.). "Anatomy and Cranial Functional Morphology of the Small-Bodied Dinosaur Fruitadens haagarorum from the Upper Jurassic of the USA". PLoS ONE. 7 (4): e31556. doi:10.1371/journal.pone.0031556. PMC 3324477. PMID 22509242.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ [Digitalisat "A tooth-bearing maxilla referable to Lycorhinus angustidens Haughton, 1924 (Dinosauria, Ornithischia)"]. Annals of the South African Museum. 99 (10): 367–380. 1990.
{{cite journal}}: Check|url=value (help); Unknown parameter|authors=ignored (help) - ^ Cite error: The named reference
sereno161was invoked but never defined (see the help page). - ^ a b c Norman, D. B.; Crompton, A. W.; Butler, R. J.; Porro, L. B.; Charig, A. J. (2011). "The Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962: Cranial anatomy, functional morphology, taxonomy, and relationships". Zoological Journal of the Linnean Society: no. doi:10.1111/j.1096-3642.2011.00697.x.
- ^ a b c d "Heterodontosaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 37. ISBN 0-7853-0443-6.
- ^ https://archive.org/stream/annalsofsouth79197980sout/#page/159/mode/1up
- ^ Santa Luca, A. P.; Crompton, A. W.; Charig, A. J. (1976). "A complete skeleton of the Late Triassic ornithischian Heterodontosaurus tucki". Nature. 264 (5584): 324. Bibcode:1976Natur.264..324S. doi:10.1038/264324a0.
- ^ Sereno, Paul C. (2012). "Taxonomy, morphology, masticatory function and phylogeny of heterodontosaurid dinosaurs". ZooKeys. 226: 1–225. doi:10.3897/zookeys.226.2840. PMC 3491919. PMID 23166462.
{{cite journal}}: Unknown parameter|laydate=ignored (help); Unknown parameter|laysource=ignored (help); Unknown parameter|laysummary=ignored (help)CS1 maint: unflagged free DOI (link) - ^ Tiny Juvenile Dinosaur Fossil Sheds Light on Evolution of Plant Eaters Newswise, Retrieved on October 23, 2008.
- ^ Crompton, A. W.; Charig, A. J. (1962). "A new Ornithischian from the Upper Triassic of South Africa". Nature. 196 (4859): 1074. Bibcode:1962Natur.196.1074C. doi:10.1038/1961074a0.
- ^ Butler, R. J.; Porro, L. B.; Norman, D. B. (2008). "A juvenile skull of the primitive ornithischian dinosaur Heterodontosaurus tuckifrom the 'Stormberg' of southern Africa". Journal of Vertebrate Paleontology. 28 (3): 702. doi:10.1671/0272-4634(2008)28[702:AJSOTP]2.0.CO;2.
- ^ R. J. Butler, J. Liyong, C. Jun, P. Godefroit (2011). "The postcranial osteology and phylogenetic position of the small ornithischian dinosaur Changchunsaurus parvus from the Quantou Formation (Cretaceous: Aptian–Cenomanian) of Jilin Province, north-eastern China". Palaeontology. 54 (3): 667–683. doi:10.1111/j.1475-4983.2011.01046.x.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
Sources
- Ingrid Cranfield, ed. (2000). Dinosaurs and other prehistoric creatures. Salamander Books. pp. 132–135.
