Iguanacolossus

Iguanacolossus (meaning Iguana Colossus from the genus name Iguana and the Latin word Colossus) is a genus of herbivorous iguanodontian dinosaur. It is a basal iguanodontian which lived during the Early Cretaceous period in what is now Utah, United States; known from UMNH VP 20205, the associated holotype with a partial skeleton of a single individual.[1]

Iguanacolossus
Temporal range: Lower Cretaceous, 130 Ma
Life restoration of Iguanacolossus
Life restoration of Iguanacolossus fortis
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Suborder: Ornithopoda
Clade: Styracosterna
Genus: Iguanacolossus
McDonald et al., 2010
Species
  • I. fortis McDonald et al., 2010 (type)

Discovery and naming

The holotype of Iguanacolossus, UMNH VP 20205, was discovered by Donald D. DeBlieux in 2005, unearthed from the Yellow Cat Member of the Cedar Mountain Formation, Utah; dating from the Barremian stage in the Early Cretaceous, it wasn't named and described until 2010 by Andrew T. McDonald, James I. Kirkland, Donald D. DeBlieux, Scott K. Madsen, Jennifer Cavin, Andrew R. C. Milner, and Lukas Panzarin, along with the genus Hippodraco, also from the Cedar Mountain Formation. UMNH VP 20205 is assigned to a single individual, featuring skull and body fragments. The generic name, Iguanacolossus, is a combination of the reptile genus Iguana, and the Latin word Colossus (meaning colossal and/or giant) in relation to the iconic Iguana-like teeth of iguanodonts and the notorious large body size of the holotype, the specific name, fortis, means mighty. The binomial means Mighty Iguana Colossus.[1]

Description

Iguanacolossus size
Estimated size of Iguanacolossus
Reconstruction of Iguanacolossus
Diagram showing the known fossil elements

Iguanacolossus is a large, robust iguanodontid, probably reaching 9 m (30 ft) long, or a size similar to Iguanodon. The unearthed holotype is fragmentary, recovered remains include skull elements: fragmented predentary, partial right maxilla, right squamosal, teeth, right and left quadrates. Body remains include: vertebrae (cervical, dorsal and caudal), chevrons, right scapula, right ilium, right pubis, right metatarsals and left fibula.[1]

It had stock metatarsals and a prominent left fibula measuring 63.0 cm (24.8 in). The maxilla preserves 14 alveoli, the presence of two concave surfaces suggest an eliptical and elongate antorbital fossa. Based on comparisons with Camptosaurus and Dakotadon, the two isolated teeth are clasiffied as dentary and maxillary, having a shield-shaped crown and lozenge-shaped crown respectively. The scapular bone is almost complete; a denticle is preserved on the predentary, various vertebrae indicate a very iguanodontian-like body shape, specially dorsal vertebrae. The two right metatarsals are classified as Metatarsals III and IV based on Camptosaurus and Iguanodon. The right pubis shows derived and plesiomorphic features, seen on related iguanodonts such as Camptosaurus, Iguanodon and Corythosaurus.[1]

Paleoecology

Cedar Mountain Formation Yellow Poison Fauna
Iguanacolossus next to contemporaneous fauna from the Yellow Cat and Poison Strip Members (Iguanacolossus in green)

Iguanacolossus was recovered from the Yellow Cat Member, it shared its environment with the Poison Strip Member fauna in the Cedar Mountain Formation, the complete fauna includes dromaeosaurids: Utahraptor and Yurgovuchia; the troodontid Geminiraptor; therizinosaurids: Falcarius and Martharaptor; the ornithomimid Nedcolbertia; the polacanthine Gastonia; sauropods: Cedarosaurus, Venenosaurus, Mierasaurus and Moabosaurus. Other contemporaneous include other iguanodontians: Hippodraco, Cedrorestes and Planicoxa. Mammal, fish, turtle, crocodile and bird fossils are known from the formation.[2]. Additional dromaeosaurids were unearthed from the Yellow Cat Member: UMNH VP 21752 (indeterminate velociraptorine) and UMNH VP 20209 (indeterminate eudromaeosaur).[3]

References

  1. ^ a b c d McDonald AT, Kirkland JI, DeBlieux DD, Madsen SK, Cavin J, et al. (2010). "New Basal Iguanodonts from the Cedar Mountain Formation of Utah and the Evolution of Thumb-Spiked Dinosaurs". PLoS ONE. 5 (11): e14075. doi:10.1371/journal.pone.0014075. PMC 2989904. PMID 21124919.
  2. ^ Paul, Gregory S. (2016). The Princeton Field Guide to Dinosaurs (2nd Edition). Princeton, New Jersey: Princeton University Press. pp. 151, 163, 229, 252, 314, 319, 326, 327. ISBN 9780691167664.
  3. ^ Senter, P.; Kirkland, J. I.; Deblieux, D. D.; Madsen, S.; Toth, N. (2012). Dodson, Peter (ed.). "New Dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous of Utah, and the Evolution of the Dromaeosaurid Tail". PLoS ONE. 7 (5): e36790. doi:10.1371/journal.pone.0036790. PMC 3352940. PMID 22615813.
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Ankylopollexia is an extinct clade of ornithischian dinosaurs that lived from the Late Jurassic to the Late Cretaceous. It is a derived clade of iguanodontian ornithopods and contains the subgroup Styracosterna.

The name stems from the Greek word, “ankylos”, mistakenly taken to mean stiff, fused (in fact the adjective means bent or curved; used of fingers, it can mean hooked), and the Latin word, “pollex”, meaning thumb. Originally described in 1986 by Sereno, this most likely synapomorphic feature of a conical thumb spine defines the clade.First appearing around 156 million years ago, in the Jurassic, Ankylopollexia became an extremely successful and widespread clade during the Cretaceous, and were found around the world. The group died out at the end of the Maastrichtian. Even though they grew to be quite large, comparable to some carnivorous dinosaurs, they were universally herbivorous. Most ankylopollexians were bipedal.

Aralosaurini

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Canardia

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Cumnoria

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Elasmaria

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Hadrosauroidea

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Hippodraco

Hippodraco (meaning Horse Dragon from the Greek word άλογο/Hippos, and the Latin word Draco) is a genus of herbivorous iguanodontian dinosaur. It is a basal iguanodontian which lived during the Early Cretaceous period during the Barremian stage in what is now Utah, United States. It contains a single species: Hippodraco scutodens. The holotype is assigned to a single immature individual: UMNH VP 20208.

Huxleysaurus

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Iguanodontia

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Laiyangosaurus

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Lapampasaurus

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Osmakasaurus

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Sahaliyania

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Theiophytalia

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Tsintaosaurini

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Xuwulong

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