View source for Timimus

{{Short description|Extinct genus of dinosaurs}}
{{speciesbox
| fossil_range = [[Early Cretaceous]] {{fossilrange|106}}
| image = Timimus.tif
| image_caption = [[Holotypic]] left femur of ''T. hermani'', NMV P186303
| genus = Timimus
| parent_authority = Rich & Vickers-Rich, 1993
| species = hermani
| authority = Rich & Vickers-Rich, 1993
}}
'''''Timimus''''' is a [[genus]] of small [[coelurosauria]]n [[Theropoda|theropod]] [[dinosaur]] from the [[Early Cretaceous]] of [[Australia]]. It was originally identified as an [[ornithomimosaur]], but now it is thought to be a different kind of theropod, possibly a [[tyrannosauroid]].<ref name=Tyrannosaur>{{Cite journal | last1 = Benson | first1 = R. B. J. | last2 = Rich | first2 = T. H. | last3 = Vickers-Rich | first3 = P. | last4 = Hall | first4 = M. | editor1-last = Farke | editor1-first = Andrew A | title = Theropod Fauna from Southern Australia Indicates High Polar Diversity and Climate-Driven Dinosaur Provinciality | doi = 10.1371/journal.pone.0037122 | journal = PLOS ONE | volume = 7 | issue = 5 | pages = e37122 | year = 2012 | pmid =  22615916| pmc = 3353904| doi-access = free | bibcode = 2012PLoSO...737122B }}</ref>
==Discovery and species==
In 1991, two [[femur|femora]] (thighbones), one from an adult and one from a juvenile, were found within a metre of each other at the [[Dinosaur Cove|Dinosaur Cove East]] site, in the small "Lake Copco" quarry, at the southern tip of [[Australia]].
The [[type species]], ''Timimus hermani'', was formally named and shortly described by Dr [[Tom Rich|Thomas Rich]] and his wife [[Patricia Vickers-Rich]] in 1993/1994. The generic name means "Tim's Mimic" and combines the name of both the discoverers' son Timothy Rich and palaeontologist [[Tim Flannery]] with a [[Latin]] ''mimus'', "mimic", a reference to the presumed affinity of the species with the [[Ornithomimosauria]]. The [[specific name (zoology)|specific name]] honours volunteer John Herman who, for many years, assisted the Dinosaur Cove project.<ref name="Rich1994">{{cite journal|author1=T.H. Rich|author2=P. Vickers-Rich|year=1994|title=Neoceratopsians and ornithomimosaurs: dinosaurs of Gondwana origin?|journal=National Geographic Research and Exploration|volume=10|issue=1|pages=129–131}}</ref>
[[File:Timimus femur.jpg|thumb|left|Colour photo of the left femur]]
The [[holotype]] specimen, NMV P186303, was found in a layer of the [[Eumeralla Formation]], dating to the [[Albian]] [[faunal stage]] in the early [[Cretaceous]], some 106&nbsp;million years ago. It consists of a left femur of an adult individual.<ref name="Rich1994" />
In 1994, Dr. Thomas Rich commented that, while it would have been more ideal to have had the most complete specimen possible as a [[holotype]], it was highly unlikely that future material of ''Timimus'' would be found, due to the limited nature of sites to be explored in the area. Also, the holotype would have had characteristics which both identified it as an ornithomimosaur and a new genus within that group. Thus the name would serve as a reference point for the material within paleontological literature. Rich stated: "By themselves, the names of dinosaurs are like telephone numbers - they are labels that go with specimens and the ideas that flow from the analysis of the material. Confusing labels, like an inaccurate telephone book, lead to an unworkable system, so one must be careful in putting names or labels on things. But the act of doing so is not creating those specimens or the ideas associated with them; it is merely creating a convenient "handle" for purposes of communication".<ref>{{cite journal|author=Rich T.H.|year=1994|title=Naming a new Genus & Species of Dinosaur on the basis of a Single Bone.|journal=Dinosaur Report|pages=10&ndash;11}}</ref>
The second femur, that of a juvenile, was assigned as the [[paratype]] specimen NMV P186323. However, based on differences between the two femora that were likely unrelated to [[Biological specificity#Conspecific|conspecific]] [[allometry]] or [[ontogeny]], later researchers have suggested that the paratype femur may instead represent an indeterminate [[maniraptora]]n.<ref name=Tyrannosaur/> Some [[vertebra]]e from the site have been referred to the also been referred to ''Timimus'', as well as some other South Australian material.{{Citation needed|date=October 2023}}
==Description==
[[File:Timimus Skeletal V1.svg|thumb|''Timimus'' restored as a tyrannosauroid, with the holotype femur shown in place]]The holotype thighbone is 44 centimetres long. From this, a total length of the animal of 2.5 metres has been extrapolated.<ref name="long1998">Long, J.A. (1998). ''Dinosaurs of Australia and New Zealand and Other Animals of the Mesozoic Era'', Harvard University Press, p. 108</ref> The slenderness of the bone suggest a lithe animal. The paratype femur is 19.5 centimetres long. The femora show several features that were considered diagnostic. There is no extensor groove between the condyles of the lower joint, which would have been a basal trait for an ornithomimosaur.<ref name="long1998"/> The femoral head is anteroposteriorally flattened. The anterior trochanter is in a high position and reaches the level of the major trochanter. In 2016 the NMV P186303 specimen was estimated to be 4.3 meters (14 ft) long, and 200 kg (441 lbs) in weight.<ref>{{Cite book|last=Molina-Pérez & Larramendi|title=Récords y curiosidades de los dinosaurios Terópodos y otros dinosauromorfos|publisher=Larousse|year=2016|location=Spain|pages=265}}</ref>
==Phylogeny==
In 1994, the describers assigned ''Timimus'' to the "Ornithomimosauridae", with which the [[Ornithomimidae]] were meant. Ornithomimosaur remains from [[Gondwana]] are rare and dubious; ''Timimus'' was thus presented as proof that the group was indeed present in the [[Southern Hemisphere]] and would even have originated there. Immediately, however, a position within the Ornithomimosauria was doubted by [[Thomas Holtz]].<ref>Holtz, T. R., Jr. 1994. "The phylogenetic position of the Tyrannosauridae: Implications for theropod systematics". ''Journal of Paleontology'' '''68''': 1100-1117</ref> Today, it is recognised that ''Timimus'' shares no derived traits, [[synapomorphies]], with the Ornithomimosauria and thus any proof it would belong to this group is lacking. It perhaps belongs to some coelurosaurian group; some workers consider it a ''[[nomen dubium]]''.<ref>S.A. Hocknull, M.A. White, T.R. Tischler, A.G. Cook, N.D. Calleja, T. Sloan, and D.A. Elliot. 2009. "New mid-Cretaceous (latest Albian) dinosaurs from Winton, Queensland, Australia". ''PLoS ONE'' '''4'''(7):e6190: 1-51</ref> A 2012 study found it to be a valid [[tyrannosauroid]],<ref name=Tyrannosaur/> a conclusion supported by Delcourt and Grillo (2018).<ref>Rafael Delcourt; Orlando Nelson Grillo (2018). "Tyrannosauroids from the Southern Hemisphere: Implications for biogeography, evolution, and taxonomy". Palaeogeography, Palaeoclimatology, Palaeoecology. in press. doi:10.1016/j.palaeo.2018.09.003.</ref>
==Paleobiology==
The [[habitat]] of ''Timimus'' consisted of [[Polar forests of the Cretaceous|polar forests]] with mild summers but cold and dark winters due to the closer proximity of the area to the [[South Pole]] during the Early Cretaceous. In 1996, [[Anusuya Chinsamy-Turan|Anusuya Chinsamy]], an expert on the microstructure of fossil bones, examined bone material from ''Timimus'' and  ''[[Leaellynasaura]]'' and discovered they exhibited different bone histology. The [[ornithischia]]n showed a continuous rate of bone deposition, while the coelurosaur had a cyclical pattern of bone formation, which suggested ''Timimus'' may have hibernated in colder months.<ref>Chinsamy, A., Rich, T., and Rich-Vickers, P. (1996). "Bone histology of dinosaurs from Dinosaur Cove, Australia", ''Journal of Vertebrate Paleontology'' '''16'''(Supplement to No.3), 28A</ref> A possible ''Timimus hermani'' or related form from the [[Strzelecki Group]] near [[Inverloch, Victoria]] left a fossil of the first phalanx of its third toe with a depressed fracture on the [[plantar]] surface.<ref name="molnar-paleopathology">Molnar, R. E., 2001, Theropod paleopathology: a literature survey: In: Mesozoic  Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University  Press, p. 337-363.</ref>
==Notes==
{{Reflist}}
==References==
* {{cite book|vauthors=Rich TH, Vickers-Rich P |year=2000|title=Dinosaurs of Darkness|publisher=Allen & Unwin|isbn=1-86508-496-4}}
* {{cite journal|doi=10.1080/02724634.1998.10011066|vauthors=Chinsamy A, Rich TH, Vickers-Rich P |year=1998|title=Polar dinosaur bone histology.|journal=Journal of Vertebrate Paleontology|volume = 18|issue = 2|pages=385&ndash;390|bibcode=1998JVPal..18..385C }}
==External links==
*[http://www.alphalink.com.au/~dannj/timimus.htm Dann's Dinosaur Info: Timimus]
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[[Category:Early Cretaceous dinosaurs of Australia]]
[[Category:Tyrannosaurs]]
[[Category:Fossil taxa described in 1993]]
[[Category:Taxa named by Patricia Vickers-Rich]]
[[Category:Taxa named by Tom Rich]]
[[Category:Paleontology in Victoria (state)]]