Iguanodontidae
Iguanodontids | |
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Royal Belgian Institute of Natural Sciences , Brussels
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | †Ornithischia |
Clade: | †Ornithopoda |
Clade: | † Hadrosauriformes
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Family: | †Iguanodontidae Bonaparte, 1850 |
Subgroups | |
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Iguanodontidae is a family of
Characterized by their elongated maxillae, they were herbivorous and typically large in size. This family exhibited locomotive dynamism; there exists evidence for both
There is no consensus on the
Description
Skull and Mandible
The upper surface of a typical iguanodontid skull has a convex curve that extends from the snout to just past the orbit, where the skull flattens out to form a roughly level plane directly above the braincase.
Teeth
Iguanodontids are generally limited to the possession of single replacement tooth at each position, although exceptions exist. The most primitive example bears positions for 13 maxillary and 14 dentary teeth. More derived forms have a larger number of positions per row. For example, I. bernissartensis is able to accommodate up to 29 maxillary and 25 dentary teeth. Iguanodontids exhibit contact between maxillary and dentary teeth upon closure of the jaw.
Manus and Pes
The second, third, and fourth digits of the iguanodontid forelimb are close together. In some cases, it is possible that digits three and four were bound into a single structure by layers of skin, a specialized
Body
All of the
Classification
In the past, Iguanodontidae became a waste-basket for any ornithopod that did not belong in either Hadrosauridae, or the now defunct Hypsilophodontidae. A number of studies suggest that Iguanodontidae as traditionally defined is paraphyletic with respect to Hadrosauridae.[11] That is, iguanodontids represent successive steps in the acquisition of advanced hadrosaurian characteristics, and in this view cannot be defined as a single distinct clade.[12] Nevertheless, some researchers have found support for a monophyletic Iguanodontidae consisting of a handful of genera.[8][9] Some other studies, however, fail to recover the group.[6] The left cladogram was recovered in a 2015 analysis that supports a monophyletic Iguanodontidae,[9] whereas the right cladogram from 2012 study finds the group to be paraphyletic:[7]
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Palaeobiology
Locomotion
Fossilized footprints provide evidence for both quadrupedality and bipedality within iguanodontids. It is thought that iguanodontids were primarily quadrupedal but could optionally walk on two limbs. The ossification of tendons along the neural arches may have played a role in facilitating the dynamic pedality of iguanodontids, as the ossified tendons could help withstand the additional stress incurred on the backbone by standing upright.[10] Some research suggests that organism size plays a role in the determination of pedality, where larger organisms are more likely to choose to walk on all fours than their smaller counterparts.[1]
Diet
Iguanodontids are low-browsing
References
- ^ a b Galton, Peter (1976). "The Dinosaur Vectisaurus valdensis (Ornithischia: Iguanodontidae) from the Lower Cretaceous of England". Journal of Paleontology. 50 (5): 976–984.
- ^ JSTOR 4523436.
- ^ a b c d e f g Godefroit, Pascal (2012). Bernissart Dinosaurs and Early Cretaceous Terrestrial Ecosystems.
- ^ a b Weishampel, David (2012). Evolution of Jaw Mechanisms in Ornithopod Dinosaurs.
- ^ S2CID 46135813.
- ^ PMID 21124919.
- ^ PMID 22629328.
- ^ a b Godefroit P, Escuillié F, Bolotsky YL, Lauters P. 2012. A new basal hadrosauroid dinosaur from the Upper Cretaceous of Kazakhstan. In: Godefroit P, ed. Bernissart dinosaurs and Early Cretaceous terrestrial ecosystems. Bloomington & Indianapolis: Indiana University Press, 335–358.
- ^ .
- ^ a b c Lucas, Spencer (1998). Lower and Middle Cretaceous Terrestrial Ecosystems: Bulletin 14.
- ^ Sereno, Paul. "Phylogeny of the bird-hipped dinosaurs". National Geographic Research. 2: 234–256.
- S2CID 128837848.