Troodon 417844 224168404 2008-07-07T17:08:49Z Thingg 5924818 Reverted edits by [[Special:Contributions/69.121.53.112|69.121.53.112]] to last version by Firsfron (using [[WP:HG|Huggle]]) {{Taxobox | name = ''Troodon'' | fossil_range = [[Late Cretaceous]] | image = Troodont.jpg | image_width = 250px | regnum = [[Animal]]ia | phylum = [[Chordate|Chordata]] | classis = [[Reptile|Sauropsida]] | superordo = [[Dinosaur]]ia | ordo = [[Saurischia]] | subordo = [[Theropoda]] | familia = [[Troodontidae]] | genus = '''''Troodon''''' | genus_authority = [[Joseph Leidy|Leidy]], 1856 | subdivision_ranks = [[Species]] | subdivision = * ''T. formosus'' <small>[[Joseph Leidy|Leidy]], 1856</small> | synonyms = * ''Pectinodon'' <small>[[Kenneth Carpenter|Carpenter]], 1982</small> * ''Polydontosaurus'' <small>[[Charles W. Gilmore|Gilmore]], 1932</small> * ''Stenonychosaurus'' <small>[[Charles Mortram Sternberg|Sternberg]], 1932</small> }} '''''Troodon''''' (or '''''Troödon''''' in older sources) is a [[genus]] of relatively small, [[bird]]-like [[dinosaur]] from the [[Late Cretaceous]] [[Period (geology)|Period]] (75-65&nbsp;[[mya (unit)|mya]]). Discovered in 1855, it was among the first dinosaurs found in [[North America]]. Its name ({{pronEng|ˈtroʊədɒn}} "TROE-odon") is [[Ancient Greek|Greek]] for "wounding tooth", referring to the dinosaur's teeth, which bore prominent serrations. These "wounding" serrations, however, have similarities to those of herbivorous reptiles, and suggest an omnivorous diet. == Characteristics == ''Troodon'' was a small dinosaur, around 2&nbsp;[[metre|meters]] (6.5&nbsp;[[foot (unit of length)|ft]]) in length, 1&nbsp;meter (3&nbsp;ft) tall, and weighed 60&nbsp;[[kilogram]]s (130&nbsp;[[pound (mass)|lb]]). It had very long, slender limbs, suggesting that the animal was able to move quickly. It had long 'arms' that folded against the wall of the thorax like a bird's. It had large, retractable sickle-shaped claws on its second toes, which were raised off the ground when running. Because of these features scientists regard ''Troodon'' as a member of the [[Maniraptora]]. Its eyes were large (perhaps suggesting [[nocturnal]] activity) and slightly forward facing, giving ''Troodon'' some [[depth perception]]. In fact most reconstructions give ''Troodon'' eyes which point in a more forwards direction than almost any other dinosaur, which implies that it had better [[Depth perception|binocular vision]] than most dinosaurs. Their light skulls contained a capsule similar to those found in ostrich dinosaurs. ''Troodon'' had one of the largest known brains of any dinosaur, relative to its body mass (comparable to modern birds). Hence it is believed to have been one of the most intelligent dinosaurs, even more intelligent than mammals of that era. Eggs have also been discovered, in nests. == Distribution == ''Troodon'' is known from the [[Judith River Formation]] and the upper [[Two Medicine Formation]]<!-- nest site: Can. J. Earth Sci. 39: 19–26 (2002) --> of [[Montana]], the Judith River Group of [[Alberta]], the [[Horseshoe Canyon Formation]] of Alberta, the [[Alaska North Slope|North Slope]] of [[Alaska]], and in the famous [[Lance Formation|Lance]] and [[Hell Creek Formation]]s of the USA. There is some evidence that ''Troodon'' favored cooler climates, as it seems to have been particularly abundant in northern areas and during cooler intervals, such as the Early [[Maastrichtian]]. It seems unlikely that all of these fossils, which come from localities hundreds or thousands of miles apart, separated by millions of years of time, represent a single species of ''Troodon''. However, further study and more fossils are needed to determine how many species of ''Troodon'' existed. == Paleobiology == ''Troodon'' is thought to have been a [[predator]], feeding mainly on smaller animals including invertebrates and [[mammals]] and this view is supported by its [[Maniraptora]]n features (sickle claw on foot; bird-like folding arms) and apparently good [[Depth perception|binocular vision]]. Comparative study of the feeding apparatus suggests that ''Troodon'' could have been an [[omnivore]] or even an [[herbivore]]. The jaws met in a broad, U-shaped [[symphysis]] similar to that of an [[iguana]], a lizard species adapted to a plant-eating lifestyle. Additionally, the teeth of ''Troodon'' were leaf-like, bearing large serrations like those of herbivorous dinosaurs; short but broad, with wear facets on their sides. === Reproduction === Varriccho et al. (2002) have described eight ''[[Troodon]]'' nests. All of these nests are from the Two Medicine Formation of Montana. These are all in the collection of the [[Museum of the Rockies]] and their accession numbers are MOR 246, 299, 393, 675, 676, 750, 963, 1139. The first of these were discovered by John Horner in 1983. Horner (1984) found isolated bones and partial skeletons of the [[hypsilophodont]] ''Orodromeus'' very near the nests in the same horizon and described the eggs as those of ''[[Orodromeus]]''. <ref name="Horner84">Horner, John R. (1984) "The nesting behavior of dinosaurs". "Scientific American", 250:130-137.</ref> Horner and Weishampel (1996) reexamined the embryos preserved in the eggs and determined that they were those of ''Troodon'', not ''[[Orodromeus]]''.<ref name="Horner&Weishampel96">Horner, John R., Weishampel, David B. (1996) "A comparative embryological study of two ornithischian dinosaurs - a correction." "Nature" 383:256-257.</ref> Varricchio et al. (1997) made this determination with even more certainty when they described a partial skeleton of an adult ''Troodon'' (MOR 748) in contact with a clutch of at least five eggs (MOR 750), probably in a brooding position.<ref name="Varricchioetal.97">Varricchio, David J., Jackson, frankie, Borkowski, John J., Horner, John R. "Nest and egg clutches of the dinosaur ''Troodon formosus'' and the evolution of avian reproductive traits." "Nature" Vol. 385:247-250 16 January 1997.</ref> Varricchio et al (1997) described the exact structure of ''Troodon'' nests. They were built from sediments, they were dish shaped, about 100 cm in internal diameter, and with a pronounced raised rim encircling the eggs. The more complete nests had between 16 (minimum number in MOR 246) and 24 (MOR 963) eggs. The eggs are shaped like elongated teardrops, with the more tapered ends pointed downwards and imbedded about halfway in the sediment. The eggs are pitched at an angle so that, on average, the upper half is closer to the center of the nest. There is no evidence that plant matter was present in the nest. Varricchio et al.(1997) were able to extract enough evidence from the nests to infer several characteristics of ''Troodon'' reproductive biology. The results are that ''Troodon'' appears to have a type of reproduction that is intermediate between crocodiles and birds, as phylogeny would predict. The eggs are statistically grouped in pairs, which suggests that the animal had two functional oviducts, like crocodiles, rather than one, as in birds. Crocodiles lay many eggs that are small proportional to adult body size. Birds lay fewer, larger, eggs. Troodon was intermediate, laying an egg of about 0.5 kg for a 50kg adult. This is 10 times larger than reptiles of the same mass, but two ''Troodon'' eggs are roughly equivalent to the 1.1 kg egg predicted for a 50 kg bird. Varricchio et al. also found evidence for iterative laying, where the adult might lay a pair of eggs every one or two days, and then ensured simultaneous hatching by delaying brooding until all eggs were laid. MOR 363 was found with 22 empty (hatched) eggs, and the embryos found in the eggs of MOR 246 were in very similar states of development, implying that all of the young hatched simultaneously. The embryos had an advanced degree of skeletal development, implying that they were [[precocial]] or even [[superprecocial]]. The authors estimated 45 to 65 total days of adult nest attendance for laying, brooding, and hatching. The authors found no evidence that the young remained in the nest after hatching and suggested that, instead, they dispersed like hatchling crocodiles or [[megapode]] birds.<ref name="Varrichioetal.02">Varricchio, David J., Horner, John J., Jackson, Frankie D. (2002) "Embryos and eggs for the Cretaceous theropod dinosaur ''Troodon formosus''." "Journal of Vertebrate Paleontology" 22(3):564-576, September 2002,</ref> == History == [[Image:Troodon_head_neck_NHM.jpg|thumb|150px|left|Head and neck of Dale Russell's ''Troodon'' sculpture, from the [[Natural History Museum]], London.]] ''Troodon'' was originally spelled ''Troödon'' (with a [[diaeresis]]) by [[Joseph Leidy]] in [[1856]], which was officially amended to its current status by Sauvage in 1876. The ''Troodon'' tooth was originally classified as a "lacertian" ([[lizard]]) by Leidy, but re-assigned as a [[megalosaurid]] dinosaur by Nopsca in 1901 (Megalosauridae having historically been a wastebin taxon for most carnivorous dinosaurs). In 1924, Gilmore suggested that the tooth belonged to the herbivorous [[pachycephalosaur]] ''[[Stegoceras]]'', and that ''Stegoceras'' was in fact a junior synonym of ''Troodon'' (the similarity of troodontid teeth to those of herbivorous dinosaurs continues to lead many paleontologists to believe that these animals were omnivores). In 1945, [[Charles Mortram Sternberg]] rejected the possibility that ''Troodon'' was a pachycephalosaur due to its stronger similarity to the teeth of other carnivorous dinosaurs. The first specimen of ''Troodon'' that was not a tooth, then referred to its own genus (''Stenonychosaurus''), was named by Sternberg in 1932, based on a foot, fragments of a hand, and some caudal vertebrae from [[Alberta]]. A remarkable feature of these remains was the enlarged claw on the second toe, which is now recognized as characteristic of [[Deinonychosauria]]. Sternberg initially classified ''Stenonychosaurus'' as a member of the family [[Coeluridae]]. Later, Sternberg (1951) speculated that since ''Stenonychosaurus'' had a "very peculiar [[pes (zoology)|pes]]" and ''Troodon'' "equally unusual teeth", they may be closely related. Unfortunately, no comparable specimens were available at that time to test the idea. A more complete skeleton of ''Stenonychosaurus'' was described by [[Dale Russell]] in 1969, which eventually formed the scientific foundation for a famous life-sized sculpture of ''Stenonychosaurus'' accompanied by its fictional, human-like descendant, the "dinosauroid". ''Stenonychosaurus'' became a well-known theropod in the 1980s, when the feet and braincase were described in more detail. Phil Currie, reviewing the known [[Troodontidae]] in 1987, reclassified ''Stenonychosaurus inequalis'' as a junior synonym of ''Troodon formosus''. This synonymy has been widely adopted by other [[paleontology|paleontologists]], and therefore all of the specimens once called ''Stenonychosaurus'' are now referred to as ''Troodon'' in the recent scientific literature. ==Classification== The [[type (zoology)|type specimen]] of ''Troodon'' has caused problems with classification, as the entire genus is based only on a single tooth from the Judith River Formation. Since the discovery of the original tooth, [[postcranial]] material from a related animal were given the name ''Stenonychosaurus''. More complete remains of ''Stenonychosaurus'' convinced most paleontologists that it in fact was the same animal as the original tooth, so the name ''Stenonychosaurus'' was replaced with its senior synonym, ''Troodon''. Other genera, including ''Polyodontosaurus'' and ''Pectinodon'', have also been assigned to ''Troodon'' based on the assumption that this particular tooth type is limited to only a single type of dinosaur. For this reason, the future of the name ''Troodon'' itself is dubious--in similar situations, genera based on teeth have been abandoned in favor of names based on better remains. Familiar names like ''[[Deinodon]]'' and ''[[Trachodon]]'' have been abandoned in this way, and further research may require ''Troodon'' be replaced with ''Stenonychosaurus''. In a chapter of the 2005 book ''Dinosaur Provincial Park'', [[Phil Currie]] (one of the leading experts on North American troodontids) resurrects the type species of ''Stenonychosaurus'' (''S. inequalis'') within the genus ''Troodon'' as ''Troodon inequalis'' (Currie, 2005). ==The "Dinosauroid"== [[Image:dinosauroid4.jpg|thumb|A model of the hypothetical Dinosauroid.]] In 1982, paleontologist Dale Russell, curator of [[vertebrate]] fossils at the [[National Museum of Canada]] in [[Ottawa]], speculated on how [[evolution]] would have proceeded if the troodonts had survived the extincton of the dinosaurs. Russell speculated that a species like ''Troodon'' would have grown smarter and taken on a human-like appearance. Russell partnered with [[taxidermist]] and artist Ron Sequin and together they made a model of what a derived, intelligent ''Troodon'' would look like, naming their fantasy creation a "[[Dinosauroid]]" (Russell & Séguin, 1982). While a few paleontologists, such as [[David Norman (paleontologist)|David Norman]] (1985) and [[Cristiano dal Sasso]] (2004) have regarded this as a plausible line of reasoning, others, such as [[Gregory S. Paul]] (1988) and [[Thomas R. Holtz Jr.]], consider it "suspiciously human" (Paul, 1988) and argue that a large-brained, highly intelligent troodontid would retain a more standard theropod body plan. [[Darren Naish]] has suggested the [[ground hornbill]] as a better model for a hominid-mimicking terrestrial theropod.[http://darrennaish.blogspot.com/2006/08/bucorvids-post-cretaceous.html][http://darrennaish.blogspot.com/2006/11/dinosauroids-revisited.html] <!-- Deleted image removed: [[Image:dinosauroid.jpg|thumb|left|A more accurate dinosauroid, according to Darren Naish|{{deletable image-caption|1=Tuesday, 25 March 2008}}]] --> ==In popular culture== ''Troodon'' is featured in [[ITV]]'s ''[[Prehistoric Park]]'' in 2006, where it was portrayed as a highly intelligent scavenger. It was also shown in two episodes of ''[[Dinosaur Planet (TV series)|Dinosaur Planet]]''. In one, a pack of dwarf ''Troodon'' make "friends" with a ''[[Pyroraptor]]''; in another, a pack of ''Troodon'' attack a flock of ''[[Orodromeus]]''. In fiction, ''Troodon'' feature prominently in the 1994 science-fiction novel ''End of an Era'' by [[Robert J. Sawyer]], in which they are the preferred host vehicle for intelligent [[Martian]] viral invaders. Also, an intelligent saurian species very like the ''Troodon'', called the ''saurs'', appears in [[Ken MacLeod]]'s "Engines of Light" series of books. In the ''[[Star Trek]]'' novel ''First Frontier'' by [[Diane Carey]] and James Kirkland, several members of the ''[[USS Enterprise (NCC-1701)|Enterprise]]'' crew travel back in time and find that ''Troodon'' has rudimentary language and were well coordinated hunters. They also encounter evolved Troodons, called Clan Ru, from the future that were transplanted before the extinction by the [[Preservers]] and were sentient beings capable of warp travel. The ''Troodon'' to "Dinosauroid" 'Thought Experiment', as proposed by Dr. Dale Russell, has also fueled conversation in the [[Ufology|UFO community]]. John Rhodes, the original proponent for the potential for intelligence in "Dinosauroid" like cryptids, called [[Reptilian-Humanoids]] or [[Reptoids]], has an entire web site dedicated to this subject. ==References==<!-- Cretaceous Research (2002) 23, 297–305 --> * Currie, P. J. (1987). "Bird-like characteristics of the jaws and teeth of troodontid [[theropod]]s (Dinosauria, Saurischia)." ''Journal of Vertebrate Paleontology'', '''7''': 72-81. * Currie, P. J. (2005). "Theropods including birds." In: Currie & Koppelhus, ''Dinosaur Provincial Park'', Indiana University Press, Bloomington. Pp 367-397. * Norman, D. B. (1985). ''The Illustrated Encyclopedia of Dinosaurs.'' Salamander Books, London. * Russell, D. A. and Séguin, R. (1982). "Reconstruction of the small Cretaceous theropod ''Stenonychosaurus inequalis'' and a hypothetical dinosauroid." ''Syllogeus'', '''37''', 1-43. * Russell, D. A. (1987). "Models and paintings of North American dinosaurs." In: Czerkas, S. J. & Olson, E. C. (eds) ''Dinosaurs Past and Present, Volume I.'' Natural History Museum of Los Angeles County/University of Washington Press (Seattle and Washington), pp. 114-131. <References /> == External links == * [http://www.dinoruss.org/de_4/5a6725e.htm ''Troodon'' in The Dinosaur Encyclopaedia] at Dino Russ's Lair * [http://paleozoo.geozoo.org/world/na/us/mt/2.php Prehistoric Montana] * [http://paleo.amnh.org/fossil/class.html?jump=SaurischiaC American Museum of Natural History] * [http://www.daviddarling.info/encyclopedia/D/dinosaurintell.html Dinosauroid] {{portalpar|Dinosaurs}} [[Category:Cretaceous dinosaurs]] [[Category:Dinosaurs of North America]] [[Category:Troodontids]] [[ca:Troodon]] [[cs:Troodon]] [[de:Troodon]] [[es:Troodon]] [[eo:Troodonto]] [[fr:Troödon]] [[id:Troodon]] [[it:Troodon formosus]] [[nl:Troodon]] [[ja:トロオドン]] [[no:Troodon]] [[pl:Troodon]] [[pt:Troodonte]] [[simple:Troödon]] [[sk:Troodon]] [[fi:Troodon]] [[sv:Troodon]] [[zh:傷齒龍]]