1053:
1076:
They graphed correlations between this ratio and the type of parenting strategies used by extant birds and crocodiles and found that the ratio in the troodont was consistent with that in birds where only the adult male broods the eggs. From this they concluded that troodont females likely did not brood eggs, that the males did, and this may be a character shared between maniraptoran dinosaurs and basal birds. However, a later analysis of avian clutch mass found that the type of parental care cannot be determined using conventional allometric methods such as the one used by
Varricchio et al.
853:
1064:
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. The Two
Medicine troodont was intermediate, laying an egg of about 0.5 kg (1.1 lb) for a 50 kg (110 lb) adult. This is 10 times larger than reptiles of the same mass, but two troodont eggs are roughly equivalent to the 1.1 kg (2.4 lb) egg predicted for a 50 kg (110 lb) bird.
903:
486:
143:
125:
998:
807:
778:. Russell also speculated that the "Dinosauroid" would have had a toothless beak. As with most modern reptiles (and birds), he conceived of its genitalia as internal. Russell speculated that it would have required a navel, as a placenta aids the development of a large brain case. However, it would not have possessed mammary glands, and would have fed its young, as some birds do, on regurgitated food. He speculated that its language would have sounded somewhat like
2520:
1085:
2497:
734:
1049:
24 (MOR 963) eggs. The eggs are shaped like elongated teardrops, with the more tapered ends pointed downwards and embedded 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.
1048:
Varricchio et al. (1997) described the exact structure of the nests. They were built from sediments, they were dish shaped, about 100 cm (39 in) 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
761:
or EQ (the relative brain weight when compared to other species with the same body weight) among the dinosaurs. Russell had discovered the first
Troodontid skull, and noted that, while its EQ was low compared to humans, it was six times higher than that of other dinosaurs. Russell suggested that if
1067:
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
1063:
Varricchio et al.(1997) were able to extract enough evidence from the nests to infer several characteristics of troodont reproductive biology. The results are that they appear to have had a type of reproduction that is intermediate between crocodiles and birds, as phylogeny would predict. The eggs
1075:
Varricchio et al. (2008) examined the bone histology of Two
Medicine troodont specimen MOR 748 and found that it lacked the bone resorption patterns that would indicate it was an egg-laying female. They also measured the ratio of the total volume of eggs in clutches to the body mass of the adult.
863:
had one of the largest known brains of any dinosaur, relative to its body mass (comparable to modern birds). This has been calculated as a cerebrum-to-brain-volume ratio 31.5% to 63% of the way from a non-avian reptile proportion to a truly avian one. Additionally, it had bony cristae supporting
593:
However, the concept that all Late
Cretaceous North American troodontids belong to one species began to be questioned soon after Currie's 1987 paper was published, including by Currie himself. Currie and colleagues (1990) noted that, while they believed the Judith River troodontids were all
773:
had semi-manipulative fingers, able to grasp and hold objects to a certain degree, and binocular vision. Russell proposed that his "Dinosauroid", like members of the troodontid family, would have had large eyes and three fingers on each hand, one of which would have been partially
797:
has argued that a large-brained, highly intelligent troodontid would retain a more standard theropod body plan, with a horizontal posture and long tail, and would probably manipulate objects with the snout and feet in the manner of a bird, rather than with human-like "hands".
955:. There are pits at the intersections of the denticles, and the points of the denticles point towards the tip, or apex, of each tooth. The teeth show wear facets on their sides. Holtz (1998) also noted that characteristics used to support a predatory habit for
540:, reviewing the pertinent specimens in 1987, showed that supposed differences in tooth and jaw structure among troodontids and saurornithoidids were based on age and position of the tooth in the jaw, rather than a difference in species. He reclassified
766:
evolution had continued to the present, its brain case could by now measure 1,100 cm (67 cu in), comparable to that of a human (on average, 1,260 cm (77 cu in) for men and 1,130 cm (69 cu in) for women).
1068:
246 were in very similar states of development, implying that all of the young hatched approximately simultaneously. The embryos had an advanced degree of skeletal development and empty eggs were relatively uncrushed, implying that hatchlings were
574:, but this reclassification, along with many other unilateral synonymizations of well known genera, was not adopted by other researchers. Currie's classification of all North American troodontid material in the single species
1424:
van der Reest, A. J.; Currie, P. J. (2017). "Troodontids (Theropoda) from the
Dinosaur Park Formation, Alberta, with a description of a unique new taxon: implications for deinonychosaur diversity in North America".
428:
by
Sternberg in 1932, based on a foot, fragments of a hand, and some tail vertebrae. A remarkable feature of these remains was the enlarged claw on the second toe, which is now recognized as characteristic of early
829:. They had very long, slender hind limbs, suggesting that these animals were able to run quickly. They had large, retractable, sickle-shaped claws on the second toes, which were raised off the ground when running.
1650:
Larsson, H.C.E. (2001). "Endocranial anatomy of
Carcharodontosaurus saharicus (Theropoda: Allosauroidea) and its implications for theropod brain evolution". In Tanke, D.H.; Carpenter, K.; Skrepnick, M.W. (eds.).
691:
include several frontals (UALVP 5282, TMP 1986.078.0040, TMP 1988.050.0088, TMP 1991.036.0690), a partial dentary (TMP 1982.019.0151), and the distal portion of a left metatarsal III (TMP 1998.068.0090).
1041:(MOR 748) in contact with a clutch of at least five eggs (MOR 750), probably in a brooding position. Van der Reest and Currie considered it possible that the Two Medicine troodont was the same species as
1665:
Holtz, Thomas R., Brinkman, Daniel L., Chandler, Chistine L. (1998) Denticle
Morphometrics and a Possibly Omnivorous Feeding Habit for the Theropod Dinosaur Troodon. Gaia number 15. December 1998. pp.
1052:
785:
However, Russell's thought experiment has been met with criticism from other paleontologists since the 1980s, many of whom point out that his
Dinosauroid is overly anthropomorphic.
482:, and a complete left foot. A couple of cranial specimens were also referred to the genus: UALVP 52611 (a nearly complete skull roof) and TMP 1986.036.0457 (a partial braincase).
757:, suggesting that it could have evolved into intelligent beings similar in body plan to humans. Over geologic time, Russell noted that there had been a steady increase in the
625:
In 2011, Zanno and colleagues reviewed the convoluted history of troodontid classification in Late Cretaceous North America. They followed Longrich (2008) in treating
1012:
in 1983 in the Two Medicine Formation of Montana. Varriccho et al. (2002) have described eight of these nests found to date. These are all in the collection of the
817:
was a small dinosaur, up to 2.5 metres (8.2 ft) in length and 35 kilograms (77 lb) in body mass. The largest specimens are comparable in size to
2633:
1720:
Horner, John R., Weishampel, David B. (1996) "A comparative embryological study of two ornithischian dinosaurs – a correction." "Nature" 383:256–257.
2648:
872:
at least in their top and bottom regions. The rest of the cristae were either cartilaginous or too delicate to be preserved. The metotic strut of
1016:
and their accession numbers are MOR 246, 299, 393, 675, 676, 750, 963, 1139. Horner (1984) found isolated bones and partial skeletons of the
1472:"Anatomical, morphometric, and stratigraphic analyses of theropod biodiversity in the Upper Cretaceous (Campanian) Dinosaur Park Formation1"
648:
In 2017, Evans and colleagues, building on the work of Zanno and others, confirmed the currently undiagnostic nature of the holotype of
1384:"A new species of troodontid theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada"
633:
almost certainly represent numerous new species, but that a more thorough review of the specimens is required. Because the holotype of
1953:
754:
1319:
Zanno, Lindsay E.; Varricchio, David J.; O'Connor, Patrick M.; Titus, Alan L.; Knell, Michael J. (2011). Lalueza-Fox, Carles (ed.).
2587:
504:
in 1969 from the Dinosaur Park Formation, which eventually formed the scientific foundation for a famous life-sized sculpture of
606:, might belong to different species. In 1991, George Olshevsky assigned the Lance formation fossils, which had first been named
2643:
1932:
1037:. Varricchio et al. (1997) made this determination with even more certainty when they described a partial skeleton of an adult
695:
In 2021, a more comprehensive re-analysis of the morphology and stratigraphic positions of known skeletal material assigned to
1631:
1526:
1290:
467:"equally unusual teeth", they may be closely related. No comparable specimens were available at that time to test the idea.
1777:
Varricchio, David J.; Horner, John J.; Jackson, Frankie D. (2002). "Embryos and eggs for the Cretaceous theropod dinosaur
656:
be used for troodontid skeletal material from the Dinosaur Park Formation. Later in 2017, Van der Reest and Currie found
618:, and several other researchers (including Currie) reverted to keeping the Dinosaur Park Formation fossils separate as
1470:
Cullen, Thomas M.; Zanno, Lindsay; Larson, Derek W.; Todd, Erinn; Currie, Philip J.; Evans, David C. (June 30, 2021).
2653:
1029:. Horner and Weishampel (1996) reexamined the embryos preserved in the eggs and determined that they were those of
441:. The second, a partial lower jaw bone, was described by Gilmore (1932) as a new species of lizard which he named
2513:
518:
became a well-known theropod in the 1980s, when the feet and braincase were described in more detail. Along with
1794:
979:
490:
1730:
Varricchio, D. J.; Jackson, F.; Borkowski, J.J.; Horner, J.R. (1997). "Nest and egg clutches of the dinosaur
474:, CMN 8539, is a partial skeleton consisting of six caudal vertebrae, hand bones, the distal end of the left
142:
986:
troodont using growth ring counts suggest that this dinosaur reached its adult size probably in 3–5 years.
629:
as a valid genus, and noted that it is likely the numerous Late Cretaceous specimens currently assigned to
1816:
Varricchio, D. J.; Moore, J. R.; Erickson, G. M.; Norell, M. A.; Jackson, F. D.; Borkowski, J. J. (2008).
1072:. The authors estimated 45 to 65 total days of adult nest attendance for laying, brooding, and hatching.
989:
A partial skeleton has been discovered with preserved puncture marks, possibly inflicted by a predator.
2578:
1925:
1867:"Evolution of parental incubation behaviour in dinosaurs cannot be inferred from clutch mass in birds"
1504:
746:
364:
1307:
Dinosaur Provincial Park, a spectacular ecosystem revealed, Part Two, Flora and Fauna from the park.
2029:
952:
758:
1593:"Bird-like characteristics of the jaws and teeth of troodontid theropods (Dinosauria, Saurischia)"
2638:
1096:
959:– the grasping hands, large brain, and stereoscopic vision – are all characteristics shared with
670:
417:
346:
528:. Based on differences in tooth structure, and the extremely fragmentary nature of the original
2605:
2540:
1711:
Horner, John R. (1984) "The nesting behavior of dinosaurs". "Scientific American", 250:130–137.
1698:
Jacobsen, A. R. 2001. Tooth-marked small theropod bone: An extremely rare trace. p. 58-63. In:
983:
354:
1282:
1276:
2600:
1918:
1057:
1013:
2628:
2523:
2083:
1829:
1743:
1555:
1434:
1395:
1336:
790:
599:
852:
719:
as the only valid troodontid taxon currently identified from the Dinosaur Park Formation.
8:
1542:
Turner, Alan H.; Mark A. Norell; Diego Pol; Julia A. Clarke; Gregory M. Erickson (2007).
1833:
1747:
1675:
Varricchio, D. J. (1993). Bone microstructure of the Upper Cretaceous theropod dinosaur
1559:
1438:
1399:
1340:
1103:, Canada, which at the time was a warm coastal floodplain covered by temperate forests.
902:
2294:
2056:
1891:
1866:
1798:
1759:
1683:
1471:
1359:
1320:
1190:
550:
367:
in 1932, based on a foot, fragments of a hand, and some caudal vertebrae from the Late
291:
137:
707:
are in fact individually variable, that both taxa overlap stratigraphically, and that
2496:
2282:
2194:
2172:
1896:
1847:
1627:
1573:
1522:
1364:
1286:
865:
525:
1802:
1325:
gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America"
2481:
2238:
1886:
1878:
1864:
1837:
1790:
1763:
1751:
1608:
1604:
1563:
1483:
1450:
1442:
1403:
1354:
1344:
947:, a lizard species adapted to a plant-eating lifestyle. Additionally, the teeth of
918:
841:
443:
2563:
2453:
2345:
2318:
2274:
2216:
2014:
1349:
1201:
1108:
972:
786:
775:
742:
603:
559:
520:
485:
479:
343:
1305:
Currie, P. (2005). "Theropods, including birds." in Currie and Koppelhus (eds).
660:
to be a valid genus, but reassigned much of the known material to the new genus
558:. Currie also made Saurornithoididae a junior synonym of Troodontidae. In 1988,
2424:
2311:
2253:
2246:
2223:
2201:
2165:
1179:
1141:
1113:
1017:
1009:
662:
313:
259:
1702:. Ed.s Tanke, D. H., Carpenter, K., Skrepnick, M. W. Indiana University Press.
1230:
2622:
1151:
1135:
1104:
884:
878:
460:
113:
68:
1842:
1817:
1568:
1543:
1541:
124:
2445:
2431:
2417:
2402:
2386:
2354:
2326:
2230:
2180:
2151:
2129:
2095:
1941:
1900:
1882:
1865:
Birchard Geoffrey F.; Ruta Marcello; Deeming D. Charles (August 23, 2013).
1851:
1577:
1487:
1446:
1407:
1368:
1168:
1163:
1157:
1146:
1129:
1023:
very near the nests in the same horizon and described the eggs as those of
1002:
997:
794:
642:
579:
501:
394:
336:
268:
239:
226:
1624:
The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals
2572:
2410:
2375:
2368:
2303:
2267:
2260:
2187:
2068:
1173:
1124:
1119:
960:
890:
819:
806:
728:
537:
380:
43:
2592:
2438:
1980:
1971:
1687:
1195:
1185:
1025:
964:
770:
438:
368:
200:
88:
53:
1455:
1084:
917:, a view supported by its sickle claw on the foot and apparently good
2474:
2395:
2041:
1989:
1755:
1069:
940:
833:
825:
779:
532:
specimens, saurornithoidids were thought to be close relatives while
213:
154:
93:
37:
30:
2534:
737:
A model of the hypothetical Dinosauroid, Dinosaur Museum, Dorchester
132:
Skeletal reconstruction, with missing parts based on related genera
2557:
2361:
2208:
1965:
1592:
1544:"A Basal Dromaeosaurid, And Size Evolution, Preceding Avian Flight"
936:
928:
914:
869:
509:
339:
187:
174:
83:
78:
63:
58:
48:
2467:
2334:
1998:
1100:
967:
675:
430:
421:
416:
that were not teeth were both found by Sternberg in 1928, in the
385:
372:
350:
301:
98:
73:
1729:
1318:
1959:
1910:
944:
931:. One comparative study of the feeding apparatus suggests that
164:
1383:
1256:
Currie, P. (1987). "Theropods of the Judith River Formation".
733:
703:
determined that several characters described as diagnostic of
1815:
1382:
Evans, D. C.; Cullen, T. M.; Larson, D. W.; Rego, A. (2017).
590:
in the scientific literature through the early 21st century.
475:
404:
and also later in the same year by Van der Reest and Currie.
1795:
10.1671/0272-4634(2002)022[0564:EAEFTC]2.0.CO;2
832:
Their eyes were very large (perhaps suggesting a partially
536:
was considered a dubious possible relative of the family.
489:
Head and neck of Dale Russell and Ron Seguin's sculpture,
749:
in Ottawa, conjectured a possible evolutionary path for
598:, troodontid fossils from other formations, such as the
1776:
1714:
1258:
Occasional Paper of the Tyrrell Museum of Palaeontology
1469:
1381:
275:
1626:. London, UK: Marshall Editions. pp. 112–113.
1423:
1809:
1692:
1519:The Princeton Field Guide to Dinosaurs 2nd Edition
1309:Indiana University Press, Bloomington. Pp 367–397.
1734:and the evolution of avian reproductive traits".
1723:
1231:"Reconstruction of the small Cretaceous theropod
951:bore large serrations, each of which is called a
2620:
1770:
1419:
1417:
836:lifestyle), and slightly forward facing, giving
1507:Darren Naish: Tetrapod Zoology, April 23, 2011.
2013:
1645:
1643:
927:teeth, however, are different from most other
906:Restoration of two individuals playing in snow
722:
1926:
1659:
1414:
1228:
1224:
1222:
1220:
1218:
335:(meaning "narrow claw lizard") is a genus of
1375:
745:, then curator of vertebrate fossils at the
2149:
1655:. Indiana University Press. pp. 19–33.
1640:
1584:
1521:. Princeton University Press. p. 160.
1008:Dinosaur eggs and nests were discovered by
876:was enlarged from side-to-side, similar to
389:, which was reverted by the recognition of
2634:Late Cretaceous dinosaurs of North America
1933:
1919:
1621:
1215:
412:The first specimens currently assigned to
123:
1890:
1841:
1818:"Avian Paternal Care Had Dinosaur Origin"
1567:
1454:
1358:
1348:
1299:
1281:. New York: Simon and Schuster. pp.
1249:
1705:
1677:Troodon formosus. J. Vertebr. Paleontol.
1268:
1083:
1051:
996:
901:
851:
805:
732:
484:
2649:Taxa named by Charles Mortram Sternberg
1649:
793:, consider it "suspiciously human" and
582:, and all of the specimens once called
447:. Later, in 1951, Sternberg recognized
407:
2621:
1590:
1499:
1497:
1255:
847:
673:troodontid specimens once referred to
393:as a separate genus from the possibly
2539:
2538:
1952:
1914:
755:Cretaceous–Paleogene extinction event
1615:
1516:
1312:
1274:
939:. The jaws met in a broad, U-shaped
1494:
1229:Russell, D. A.; SĂ©guin, R. (1982).
637:is a single tooth, this may render
13:
1783:Journal of Vertebrate Paleontology
1597:Journal of Vertebrate Paleontology
1476:Canadian Journal of Earth Sciences
1427:Canadian Journal of Earth Sciences
1388:Canadian Journal of Earth Sciences
353:, Canada, as well as possibly the
321:(van der Reest & Currie, 2017)
14:
2665:
433:. Sternberg initially classified
2519:
2518:
2495:
1940:
1278:Predatory Dinosaurs of the World
753:, if it had not perished in the
687:. The specimens now referred to
512:descendant, the "dinosauroid".
141:
41:
1858:
1669:
1535:
1510:
1235:and a hypothetical dinosauroid"
1079:
992:
897:
679:have recently been referred to
578:became widely adopted by other
1609:10.1080/02724634.1987.10011638
1463:
1088:Reconstructed skeleton (right)
801:
508:accompanied by its fictional,
491:Natural History Museum, London
1:
2644:Fossil taxa described in 1932
1208:
1001:Eggs partly encased in rock,
357:. The type and only species,
1350:10.1371/journal.pone.0024487
1321:"A new troodontid theropod,
564:Saurornithoides mongoliensis
496:A more complete skeleton of
455:, and speculated that since
7:
610:but later synonymized with
10:
2670:
1233:Stenonychosaurus inequalis
1093:Stenonychosaurus inequalis
726:
713:Stenonychosaurus inequalis
562:went farther and included
542:Stenonychosaurus inequalis
472:Stenonychosaurus inequalis
437:as a member of the family
426:Stenonychosaurus inequalis
379:was reassigned in 1987 by
280:Stenonychosaurus inequalis
2547:
2508:
2493:
2385:
2344:
2293:
2160:
2145:
2126:
2094:
2076:
2067:
2049:
2040:
2022:
2009:
1948:
982:studies performed on the
913:are thought to have been
882:and primitive birds like
747:National Museum of Canada
709:Latenivenatrix mcmasterae
451:as a possible synonym of
365:Charles Mortram Sternberg
297:
290:
274:
267:
138:Scientific classification
136:
131:
122:
23:
1700:Mesozoic Vertebrate Life
1653:Mesozoic Vertebrate Life
1622:Palmer, D., ed. (1999).
810:Size compared to a human
759:encephalization quotient
546:Polyodontosaurus grandis
444:Polyodontosaurus grandis
2654:Paleontology in Alberta
1843:10.1126/science.1163245
1569:10.1126/science.1144066
1097:Dinosaur Park Formation
711:is a junior synonym of
524:, it formed the family
418:Dinosaur Park Formation
347:Dinosaur Park Formation
1883:10.1098/rsbl.2013.0036
1591:Currie, P. J. (1987).
1505:Dinosauroids Revisited
1488:10.1139/cjes-2020-0145
1447:10.1139/cjes-2017-0031
1408:10.1139/cjes-2017-0034
1123:. Herbivores included
1089:
1060:
1005:
943:similar to that of an
907:
857:
811:
738:
554:as junior synonyms of
493:
424:. The first was named
355:Two Medicine Formation
2601:Paleobiology Database
1087:
1058:Museum of the Rockies
1055:
1014:Museum of the Rockies
1000:
905:
855:
809:
736:
488:
459:had a "very peculiar
1517:Paul, G. S. (2016).
1275:Paul, G. S. (1988).
791:Thomas R. Holtz, Jr.
600:Hell Creek Formation
586:were referred to as
408:History of discovery
1834:2008Sci...322.1826V
1748:1997Natur.385..247V
1560:2007Sci...317.1378T
1439:2017CaJES..54..919V
1400:2017CaJES..54..813E
1341:2011PLoSO...624487Z
935:could have been an
848:Brain and inner ear
652:and suggested that
2295:Jinfengopteryginae
1503:Naish, D. (2006).
1095:is known from the
1090:
1061:
1006:
908:
866:tympanic membranes
858:
812:
739:
627:Pectinodon bakkeri
608:Pectinodon bakkeri
551:Pectinodon bakkeri
494:
114:Late Maastrichtian
2616:
2615:
2541:Taxon identifiers
2532:
2531:
2504:
2503:
2491:
2490:
2283:Halszkaraptorinae
2195:Hesperornithoides
2173:Archaeornithoides
2141:
2140:
2137:
2136:
2122:
2121:
2118:
2117:
2114:
2113:
1742:(6613): 247–250.
1633:978-1-84028-152-1
1554:(5843): 1378–81.
1528:978-0-691-16766-4
1292:978-0-671-61946-6
1191:pachycephalosaurs
980:Age determination
723:The "Dinosauroid"
620:Troodon inequalis
526:Saurornithoididae
500:was described by
400:in 2017 by Evans
328:
327:
322:
309:
308:(Sternberg, 1932)
263:
117:
16:Theropod dinosaur
2661:
2609:
2608:
2596:
2595:
2583:
2582:
2581:
2579:Stenonychosaurus
2568:
2567:
2566:
2549:Stenonychosaurus
2536:
2535:
2522:
2521:
2499:
2461:Stenonychosaurus
2239:Polyodontosaurus
2158:
2157:
2147:
2146:
2074:
2073:
2047:
2046:
2020:
2019:
2011:
2010:
2004:
2003:
1950:
1949:
1935:
1928:
1921:
1912:
1911:
1905:
1904:
1894:
1862:
1856:
1855:
1845:
1828:(5909): 1826–8.
1813:
1807:
1806:
1779:Troodon formosus
1774:
1768:
1767:
1756:10.1038/385247a0
1732:Troodon formosus
1727:
1721:
1718:
1712:
1709:
1703:
1696:
1690:
1673:
1667:
1663:
1657:
1656:
1647:
1638:
1637:
1619:
1613:
1612:
1588:
1582:
1581:
1571:
1548:Science Magazine
1539:
1533:
1532:
1514:
1508:
1501:
1492:
1491:
1467:
1461:
1460:
1458:
1421:
1412:
1411:
1379:
1373:
1372:
1362:
1352:
1316:
1310:
1303:
1297:
1296:
1272:
1266:
1265:
1253:
1247:
1246:
1226:
1056:Clutch of eggs,
1043:Stenonychosaurus
957:Stenonychosaurus
949:Stenonychosaurus
933:Stenonychosaurus
925:Stenonychosaurus
919:binocular vision
911:Stenonychosaurus
874:Stenonychosaurus
861:Stenonychosaurus
842:depth perception
838:Stenonychosaurus
815:Stenonychosaurus
764:Stenonychosaurus
751:Stenonychosaurus
697:Stenonychosaurus
689:Stenonychosaurus
681:Stenonychosaurus
658:Stenonychosaurus
654:Stenonychosaurus
650:Troodon formosus
631:Troodon formosus
612:Troodon formosus
584:Stenonychosaurus
576:Troodon formosus
556:Troodon formosus
530:Troodon formosus
516:Stenonychosaurus
506:Stenonychosaurus
498:Stenonychosaurus
470:The holotype of
457:Stenonychosaurus
435:Stenonychosaurus
391:Stenonychosaurus
332:Stenonychosaurus
320:
307:
277:
258:
254:Stenonychosaurus
251:
238:
225:
146:
145:
127:
111:
110:
40:
29:Temporal range:
25:Stenonychosaurus
21:
20:
2669:
2668:
2664:
2663:
2662:
2660:
2659:
2658:
2619:
2618:
2617:
2612:
2604:
2599:
2591:
2586:
2577:
2576:
2571:
2562:
2561:
2556:
2543:
2533:
2528:
2500:
2487:
2454:Saurornithoides
2381:
2346:Sinovenatorinae
2340:
2319:Liaoningvenator
2289:
2275:Anchiornithidae
2217:Liaoningvenator
2154:
2133:
2110:
2090:
2063:
2036:
2030:Avemetatarsalia
2015:Avemetatarsalia
2005:
1955:
1954:
1944:
1939:
1909:
1908:
1877:(4): 20130036.
1871:Biology Letters
1863:
1859:
1814:
1810:
1775:
1771:
1728:
1724:
1719:
1715:
1710:
1706:
1697:
1693:
1674:
1670:
1664:
1660:
1648:
1641:
1634:
1620:
1616:
1589:
1585:
1540:
1536:
1529:
1515:
1511:
1502:
1495:
1468:
1464:
1422:
1415:
1380:
1376:
1317:
1313:
1304:
1300:
1293:
1273:
1269:
1254:
1250:
1227:
1216:
1211:
1202:Foraminacephale
1082:
995:
970:and omnivorous
900:
850:
840:some degree of
804:
787:Gregory S. Paul
743:Dale A. Russell
731:
725:
616:Troodon bakkeri
614:to the species
604:Lance Formation
580:paleontologists
572:T. mongoliensis
560:Gregory S. Paul
521:Saurornithoides
410:
363:, was named by
344:Late Cretaceous
319:
306:
286:
285:Sternberg, 1932
283:
257:
249:
236:
223:
140:
118:
109:
108:
107:
106:
101:
96:
91:
86:
81:
76:
71:
66:
61:
56:
51:
46:
35:
34:
27:
17:
12:
11:
5:
2667:
2657:
2656:
2651:
2646:
2641:
2639:Campanian life
2636:
2631:
2614:
2613:
2611:
2610:
2597:
2584:
2569:
2553:
2551:
2545:
2544:
2530:
2529:
2527:
2526:
2516:
2509:
2506:
2505:
2502:
2501:
2494:
2492:
2489:
2488:
2486:
2485:
2478:
2471:
2464:
2457:
2450:
2442:
2435:
2428:
2425:Latenivenatrix
2421:
2414:
2407:
2399:
2391:
2389:
2383:
2382:
2380:
2379:
2372:
2365:
2358:
2350:
2348:
2342:
2341:
2339:
2338:
2331:
2323:
2315:
2312:Jinfengopteryx
2308:
2299:
2297:
2291:
2290:
2288:
2287:
2279:
2271:
2264:
2257:
2250:
2247:Sinornithoides
2243:
2235:
2227:
2224:Papiliovenator
2220:
2213:
2205:
2202:Jianianhualong
2198:
2191:
2184:
2177:
2169:
2166:Albertavenator
2161:
2155:
2150:
2143:
2142:
2139:
2138:
2135:
2134:
2127:
2124:
2123:
2120:
2119:
2116:
2115:
2112:
2111:
2109:
2108:
2107:
2106:
2100:
2098:
2092:
2091:
2089:
2088:
2087:
2086:
2077:
2071:
2065:
2064:
2062:
2061:
2060:
2059:
2050:
2044:
2038:
2037:
2035:
2034:
2033:
2032:
2023:
2017:
2007:
2006:
2002:
2001:
1992:
1983:
1974:
1968:
1962:
1946:
1945:
1938:
1937:
1930:
1923:
1915:
1907:
1906:
1857:
1808:
1789:(3): 564–576.
1769:
1722:
1713:
1704:
1691:
1668:
1658:
1639:
1632:
1614:
1583:
1534:
1527:
1509:
1493:
1482:(9): 870–884.
1462:
1433:(9): 919–935.
1413:
1394:(8): 813–826.
1374:
1323:Talos sampsoni
1311:
1298:
1291:
1267:
1248:
1213:
1212:
1210:
1207:
1180:Euoplocephalus
1142:Prosaurolophus
1114:Daspletosaurus
1109:tyrannosaurids
1105:Apex predators
1081:
1078:
1018:hypsilophodont
1010:John R. Horner
994:
991:
899:
896:
849:
846:
803:
800:
727:Main article:
724:
721:
715:. This leaves
705:Latenivenatrix
701:Latenivenatrix
685:Latenivenatrix
663:Latenivenatrix
409:
406:
326:
325:
324:
323:
314:Latenivenatrix
310:
295:
294:
288:
287:
284:
272:
271:
265:
264:
247:
243:
242:
234:
230:
229:
221:
217:
216:
211:
204:
203:
198:
191:
190:
185:
178:
177:
172:
168:
167:
162:
158:
157:
152:
148:
147:
134:
133:
129:
128:
120:
119:
104:
103:
102:
97:
92:
87:
82:
77:
72:
67:
62:
57:
52:
47:
42:
28:
15:
9:
6:
4:
3:
2:
2666:
2655:
2652:
2650:
2647:
2645:
2642:
2640:
2637:
2635:
2632:
2630:
2627:
2626:
2624:
2607:
2602:
2598:
2594:
2589:
2585:
2580:
2574:
2570:
2565:
2559:
2555:
2554:
2552:
2550:
2546:
2542:
2537:
2525:
2517:
2515:
2511:
2510:
2507:
2498:
2484:
2483:
2479:
2477:
2476:
2472:
2470:
2469:
2465:
2463:
2462:
2458:
2456:
2455:
2451:
2448:
2447:
2443:
2441:
2440:
2436:
2434:
2433:
2429:
2427:
2426:
2422:
2420:
2419:
2415:
2413:
2412:
2408:
2405:
2404:
2400:
2398:
2397:
2393:
2392:
2390:
2388:
2384:
2378:
2377:
2373:
2371:
2370:
2366:
2364:
2363:
2359:
2357:
2356:
2352:
2351:
2349:
2347:
2343:
2337:
2336:
2332:
2329:
2328:
2324:
2321:
2320:
2316:
2314:
2313:
2309:
2306:
2305:
2301:
2300:
2298:
2296:
2292:
2285:
2284:
2280:
2277:
2276:
2272:
2270:
2269:
2265:
2263:
2262:
2258:
2256:
2255:
2251:
2249:
2248:
2244:
2241:
2240:
2236:
2233:
2232:
2228:
2226:
2225:
2221:
2219:
2218:
2214:
2211:
2210:
2206:
2204:
2203:
2199:
2197:
2196:
2192:
2190:
2189:
2185:
2183:
2182:
2178:
2175:
2174:
2170:
2168:
2167:
2163:
2162:
2159:
2156:
2153:
2148:
2144:
2132:
2131:
2125:
2104:
2103:
2102:
2101:
2099:
2097:
2093:
2085:
2081:
2080:
2079:
2078:
2075:
2072:
2070:
2066:
2058:
2054:
2053:
2052:
2051:
2048:
2045:
2043:
2039:
2031:
2027:
2026:
2025:
2024:
2021:
2018:
2016:
2012:
2008:
2000:
1996:
1993:
1991:
1987:
1984:
1982:
1978:
1975:
1973:
1969:
1967:
1963:
1961:
1957:
1956:
1951:
1947:
1943:
1936:
1931:
1929:
1924:
1922:
1917:
1916:
1913:
1902:
1898:
1893:
1888:
1884:
1880:
1876:
1872:
1868:
1861:
1853:
1849:
1844:
1839:
1835:
1831:
1827:
1823:
1819:
1812:
1804:
1800:
1796:
1792:
1788:
1784:
1780:
1773:
1765:
1761:
1757:
1753:
1749:
1745:
1741:
1737:
1733:
1726:
1717:
1708:
1701:
1695:
1689:
1685:
1681:
1678:
1672:
1662:
1654:
1646:
1644:
1635:
1629:
1625:
1618:
1610:
1606:
1602:
1598:
1594:
1587:
1579:
1575:
1570:
1565:
1561:
1557:
1553:
1549:
1545:
1538:
1530:
1524:
1520:
1513:
1506:
1500:
1498:
1489:
1485:
1481:
1477:
1473:
1466:
1457:
1452:
1448:
1444:
1440:
1436:
1432:
1428:
1420:
1418:
1409:
1405:
1401:
1397:
1393:
1389:
1385:
1378:
1370:
1366:
1361:
1356:
1351:
1346:
1342:
1338:
1335:(9): e24487.
1334:
1330:
1326:
1324:
1315:
1308:
1302:
1294:
1288:
1284:
1280:
1279:
1271:
1263:
1259:
1252:
1244:
1240:
1236:
1234:
1225:
1223:
1221:
1219:
1214:
1206:
1204:
1203:
1198:
1197:
1192:
1188:
1187:
1182:
1181:
1176:
1175:
1170:
1166:
1165:
1160:
1159:
1154:
1153:
1152:Styracosaurus
1148:
1144:
1143:
1138:
1137:
1136:Corythosaurus
1132:
1131:
1126:
1122:
1121:
1116:
1115:
1110:
1106:
1102:
1098:
1094:
1086:
1077:
1073:
1071:
1065:
1059:
1054:
1050:
1046:
1044:
1040:
1036:
1032:
1028:
1027:
1022:
1019:
1015:
1011:
1004:
999:
990:
987:
985:
981:
977:
975:
974:
969:
966:
962:
958:
954:
950:
946:
942:
938:
934:
930:
926:
922:
920:
916:
912:
904:
895:
893:
892:
887:
886:
885:Archaeopteryx
881:
880:
879:Dromaeosaurus
875:
871:
867:
862:
854:
845:
843:
839:
835:
830:
828:
827:
822:
821:
816:
808:
799:
796:
792:
788:
783:
781:
777:
772:
768:
765:
762:the trend in
760:
756:
752:
748:
744:
735:
730:
720:
718:
714:
710:
706:
702:
698:
693:
690:
686:
682:
678:
677:
672:
671:Dinosaur Park
667:
665:
664:
659:
655:
651:
646:
644:
640:
636:
632:
628:
623:
621:
617:
613:
609:
605:
601:
597:
591:
589:
585:
581:
577:
573:
569:
566:in the genus
565:
561:
557:
553:
552:
547:
543:
539:
535:
531:
527:
523:
522:
517:
513:
511:
507:
503:
499:
492:
487:
483:
481:
477:
473:
468:
466:
462:
458:
454:
450:
446:
445:
440:
436:
432:
427:
423:
419:
415:
405:
403:
399:
396:
392:
388:
387:
383:to the genus
382:
378:
374:
370:
366:
362:
361:
356:
352:
348:
345:
341:
338:
334:
333:
317:
315:
311:
305:
303:
299:
298:
296:
293:
289:
282:
281:
273:
270:
266:
261:
256:
255:
248:
245:
244:
241:
235:
232:
231:
228:
222:
219:
218:
215:
212:
209:
206:
205:
202:
199:
196:
193:
192:
189:
186:
183:
180:
179:
176:
173:
170:
169:
166:
163:
160:
159:
156:
153:
150:
149:
144:
139:
135:
130:
126:
121:
115:
100:
95:
90:
85:
80:
75:
70:
65:
60:
55:
50:
45:
39:
32:
26:
22:
19:
2548:
2480:
2473:
2466:
2460:
2459:
2452:
2446:Philovenator
2444:
2437:
2432:Linhevenator
2430:
2423:
2418:Hypnovenator
2416:
2409:
2403:Byronosaurus
2401:
2394:
2387:Troodontinae
2374:
2367:
2360:
2355:Daliansaurus
2353:
2333:
2327:Philovenator
2325:
2317:
2310:
2302:
2281:
2273:
2266:
2259:
2252:
2245:
2237:
2231:Paronychodon
2229:
2222:
2215:
2207:
2200:
2193:
2186:
2181:Geminiraptor
2179:
2171:
2164:
2152:Troodontidae
2130:Troodontidae
2128:
2096:Troodontidae
1994:
1985:
1976:
1942:Troodontidae
1874:
1870:
1860:
1825:
1821:
1811:
1786:
1782:
1778:
1772:
1739:
1735:
1731:
1725:
1716:
1707:
1699:
1694:
1679:
1676:
1671:
1661:
1652:
1623:
1617:
1600:
1596:
1586:
1551:
1547:
1537:
1518:
1512:
1479:
1475:
1465:
1430:
1426:
1391:
1387:
1377:
1332:
1328:
1322:
1314:
1306:
1301:
1277:
1270:
1261:
1257:
1251:
1242:
1238:
1232:
1200:
1194:
1184:
1178:
1172:
1164:Chasmosaurus
1162:
1158:Centrosaurus
1156:
1150:
1140:
1134:
1130:Lambeosaurus
1128:
1125:hadrosaurids
1118:
1112:
1099:of southern
1092:
1091:
1080:Paleoecology
1074:
1066:
1062:
1047:
1042:
1038:
1034:
1030:
1024:
1020:
1007:
1003:Burke Museum
993:Reproduction
988:
984:Two Medicine
978:
971:
956:
948:
932:
924:
923:
910:
909:
898:Paleobiology
889:
883:
877:
873:
868:, that were
860:
859:
837:
831:
824:
818:
814:
813:
795:Darren Naish
784:
769:
763:
750:
740:
717:S. inequalis
716:
712:
708:
704:
700:
696:
694:
688:
684:
680:
674:
668:
661:
657:
653:
649:
647:
643:nomen dubium
638:
634:
630:
626:
624:
619:
615:
611:
607:
595:
592:
587:
583:
575:
571:
567:
563:
555:
549:
545:
541:
533:
529:
519:
515:
514:
505:
502:Dale Russell
497:
495:
471:
469:
464:
456:
452:
448:
442:
434:
425:
413:
411:
401:
397:
390:
384:
377:S. inequalis
376:
360:S. inequalis
359:
358:
331:
330:
329:
312:
300:
279:
278:
269:Type species
253:
252:
240:Troodontinae
227:Troodontidae
207:
194:
181:
24:
18:
2629:Troodontids
2573:Wikispecies
2411:Gobivenator
2376:Sinusonasus
2369:Sinovenator
2268:Xixiasaurus
2261:Tochisaurus
2188:Harenadraco
2084:Maniraptora
2069:Maniraptora
1174:Scolosaurus
1169:ankylosaurs
1147:ceratopsids
1120:Gorgosaurus
976:(raccoon).
961:herbivorous
891:Hesperornis
856:Restoration
820:Deinonychus
802:Description
789:(1988) and
771:Troodontids
729:Dinosauroid
635:T. formosus
596:T. formosus
544:as well as
538:Phil Currie
381:Phil Currie
233:Subfamily:
2623:Categories
2512:See also:
2439:Pectinodon
2105:see below↓
1981:Dinosauria
1972:Sauropsida
1682:, 99–104.
1456:1807/78296
1209:References
1196:Stegoceras
1186:Edmontonia
1035:Orodromeus
1026:Orodromeus
1021:Orodromeus
965:omnivorous
480:astragalus
449:P. grandis
439:Coeluridae
369:Cretaceous
337:troodontid
316:mcmasterae
201:Saurischia
188:Dinosauria
2564:Q35640969
2482:Zanabazar
2475:Urbacodon
2396:Borogovia
2057:Theropoda
2042:Theropoda
1990:Theropoda
1958:Kingdom:
1603:: 72–81.
1239:Syllogeus
1107:included
1070:precocial
941:symphysis
929:theropods
915:predators
834:nocturnal
826:Unenlagia
780:bird song
741:In 1982,
431:paravians
342:from the
304:inequalis
260:Sternberg
214:Theropoda
161:Kingdom:
155:Eukaryota
112:Possible
31:Campanian
2558:Wikidata
2524:Category
2514:Timeline
2209:Koparion
1966:Chordata
1964:Phylum:
1960:Animalia
1901:23676654
1852:19095938
1803:85728452
1666:159–166.
1578:17823350
1369:21949721
1329:PLOS ONE
1264:: 52–60.
1193:such as
1171:such as
1149:such as
1127:such as
1111:such as
968:primates
953:denticle
937:omnivore
870:ossified
510:humanoid
340:dinosaur
292:Synonyms
220:Family:
175:Chordata
171:Phylum:
165:Animalia
151:Domain:
36:76
2593:4822640
2468:Troodon
2335:Tamarro
1999:Paraves
1970:Class:
1892:3730617
1830:Bibcode
1822:Science
1764:4313286
1744:Bibcode
1688:4523488
1556:Bibcode
1435:Bibcode
1396:Bibcode
1360:3176273
1337:Bibcode
1283:398–399
1245:: 1–43.
1101:Alberta
1039:Troodon
1031:Troodon
973:Procyon
776:opposed
676:Troodon
639:Troodon
588:Troodon
568:Troodon
534:Troodon
465:Troodon
453:Troodon
422:Alberta
414:Troodon
398:Troodon
395:dubious
386:Troodon
373:Alberta
351:Alberta
302:Troodon
246:Genus:
105:↓
1899:
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1762:
1736:Nature
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1189:; and
1183:, and
1161:, and
1139:, and
1033:, not
945:iguana
864:their
463:" and
402:et al.
262:, 1932
116:record
2606:38571
2304:Almas
2254:Talos
1995:Clade
1986:Clade
1977:Clade
1799:S2CID
1760:S2CID
1684:JSTOR
669:Many
476:tibia
208:Clade
195:Clade
182:Clade
2588:GBIF
2082:see
2055:see
2028:see
1897:PMID
1848:PMID
1628:ISBN
1574:PMID
1523:ISBN
1365:PMID
1287:ISBN
1199:and
1117:and
888:and
823:and
699:and
683:and
602:and
548:and
478:and
44:Preęž’
2362:Mei
1887:PMC
1879:doi
1838:doi
1826:322
1791:doi
1781:".
1752:doi
1740:385
1605:doi
1564:doi
1552:317
1484:doi
1451:hdl
1443:doi
1404:doi
1355:PMC
1345:doi
963:or
570:as
461:pes
420:of
371:of
349:of
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