922:. Ecological zonation based on altitude seems to be present as well. Lehman speculates that the Judithian dinosaur faunas may represent the "climax" of "individuality" in dinosaur communities. Ecological disturbance brought them to an end during the Edmontonian. Relative sea levels fell very rapidly due to the Laramide Orogeny. Opportunistic generalist herbivores filled the vacated niches that were once filled by a diverse number of specialist forms. The newly formed ecosystems tended to be dominated by a single herbivorous species each. The new dominant herbivores were usually less ornamented and probably represent "survivors from indigenous lineages" rather than immigrants from other areas. Gradually however "relict" dinosaurs such as protoceratopsids and sauropods began expanding into lower altitude areas as sea-levels fell. In the southern biome by Lancian time sauropods had replaced both hadrosaurs and ceratopsians in the southern biome. In the north both were still present although hadrosaurs were demoted to a "subordinate" role in dinosaur ecosystems. Edmontosaurus was the dominant northern hadrosaurid. At the end of the Cretaceous most ecosystems were dominated by a single herbivore. The northern biome was dominated by
231:. In modern North America if one was to sample hypothetical future sites in southwestern Texas, northern New Mexico and southern Alberta, 34 of the 41 large mammal species in the continent could be represented, with the remainder's geographic ranges not overlapping with the sites. Roughly 20 species would be located at each site, but contrasting with the provinciality of dinosaurs, 11-16 species out of twenty would be shared between all three sites. Only the rarer species among modern mammal communities would be able to distinguish different latitudinal zones, and some of these taxa are likely too rare to fossilize. This lack of provinciality is despite the strong temperature gradient. Restrictions in herbivorous dinosaur distribution may be due to foliage preferences, narrow tolerance for variation in climate or other environmental factors. The restrictions on herbivorous dinosaur distribution must have been due to ecological factors rather than physical barriers because carnivorous dinosaurs tended to have wider distributions, especially smaller ones.
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diversity because the herbivores had specialized diets that minimized their needs to compete with one another for resources. Migration between ecosystems was probably limited due to the efficient occupation of every niche in these environments. There doesn't seem to have been any physical barrier inhibiting physical travel between the different ecological zones. The widespread prominence of hadrosaurs in these ecosystems may imply that the dominant ecosystem of the time and place were coastal wetlands. Latitudinal zonation was pervasive across these ecosystems and likely arising from similar causes as modern provinciality, which exhibits similar characteristics. Northern biomes were dominated by pachyrhinosaurs and
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level could explain some of the environmental changes occurring Late
Cretaceous western North America. The wetland habitat enjoyed by many dinosaurs would have shrunk and fragmented. Since many species had very limited geographic ranges its plausible that some of the fragments would be smaller than the area needed to support the species. However, there's no direct evidence for the shrinking of wetland environments. Lehman contends that the actual area of coastal lowlands within 150m of the shoreline must have actually increased significantly. Further, dinosaurs that inhabited inland or arid environments were among the most prevalent in the Lancian. The
930:. This faunal turnover coincides with the Laramide orogeny and the uplift of the central Rockies. Strata exhibit changes in lithology and the direction of paleocurrents, and a severe drop in relative sea level. At the very least, Lehman argues, the altitudinal life zones would shift, and a change in the distribution of vegetation utilized by herbivorous dinosaurs would have probably resulted. By the end of the Judithian, North America had 7.7 million km of land area, but by the end of the Lancian it had reached 17.9 million km, nearly the modern value of 22.5 million km.
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822:. If the geographic range of some dinosaur species were truly as limited as the fossil record suggests, then a rapid rise and in sea level could cause intense pressure even the event was local. Additionally, a rapid drop in sea level could allow for "rapid colonization by a few dinosaur generalists." The appearance or reappearance of basal
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642:. In 2006, Sullivan and Lucas refined their estimate, stating that the Kirtlandian ranged from 75 to 72.8 million years ago. Later that year, Sullivan changed the time range again, finding that the faunal age lasted only 2 million years, from 74.8 to 72.8 million years ago. More precise dating in 2010 by
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The
Kirtland and Fruitland formations both consist of the major formations in the Kirtlandian age. The Fruitland Formation measures 97 to 107 metres (318 to 351 ft) thick, and with the 594 metres (1,949 ft) of the Kirtland Formation, the Kirtlandian consists of 701 metres (2,300 ft) of
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The decline of mammal diversity in
Western North America from the Miocene to present primarily effected large herbivores and occurred over roughly the same length of time as the Late Cretaceous changes, and so may be parallel. They have many commonalities, including the replacement of diversity with
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are known from the
Kirtlandian faunal age. The Hunter Wash local fauna was defined as the vertebrates "obtained from the upper 40 feet of the Fruitland Formation and the lower 55 feet of the lower shale of the Kirtland Shale (now a formation) in Hunter Wash (member)." The Hunter Wash fauna therefore
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The extreme changes occurring in the make-up of herbivore communities during the faunal turnover suggests that a change in the ecosystems' flora was "the most immediate cause...though perhaps not the ultimate one." The rapid expansion of land and drying of inland climate accompanying a drop in sea
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are the only known surviving hadrosaurs. Both lack the elaborate ornamentation of their predecessors. In the south the transition to the
Lancian is even more dramatic, which Lehman describes as "the abrupt reemergence of a fauna with a superficially "Jurassic" aspect." These faunas are dominated by
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Dinosaur faunas of the
Judithian age may represent the peak of dinosaur evolution in North America. Hadrosaurs were universally the dominant herbivore of the period and comprised more than half of "a typical assemblage." This was also the period of greatest generic diversity among large herbivorous
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preceded the development of endemic northern and southern biomes in
Western North America during the Late Cretaceous. Environments with highly favorable conditions led to diverse ecosystems populated by ornate herbivores with complex social interactions. These ecosystems were able to support such
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was an immigrant from Asia. Inhabitants of upland environment are more likely to be endemic than coastal species, and tend to have less of an ability to cross bodies of water. Further, early cretaceous titanosaurs were already known, so North
American potential ancestors for Titanosaurus already
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deposits in North
America reveal that basal neoceratopsian were already present on the continent before their apparent reemergence in the Lancian, so an immigration event from Asia is unnecessary to explain their appearance. The major potential immigrants represent archaic forms that probably
564:, and the animals from the Fossil Forest and Ah-shi-sle-pah Wash. The Willow Wash fauna was named for all the fauna of the De-na-zin Member of the Kirtland Formation. The majority of the fauna from the Willow Wash were originally thought to belong to the Alamo Wash local fauna of the
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dinosaur distribution, concluded that they were "remarkably provincial," with herbivorous dinosaurs exhibiting "persistent latitudinal and altitudinal zonation" in "istinctive endemic associations." Provincialism was even present during the turbulent faunal turnover of the
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habitats to near-sea level coastal habitats. Modern life at high elevations in lower altitudes resembles life at low elevation in higher latitudes. There may be parallels to this phenomenon in
Cretaceous ecosystems, for instance,
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found that the second youngest ash can actually be dated more precisely than thought obtaining an error range of 0.18 million years. Longrich also dated the two older ashes, finding a date the same as that of Sullivan.
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The two main formations of the Kirtlandian, the Fruitland and Kirtland, were originally included in the older Judithian age, an interpretation superseded with the naming of the Kirtlandian. In 1975, Russell identified five
592:. Within the sediments with a Kirtlandian age, two local faunas, the Hunter Wash local fauna, and the Willow Wash local fauna, have been identified. The currently accepted date of the Kirtlandian is 74.8 to 72.8
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faunas whose large herbivores' ranges "typical ... span much of a continent." Lehman observes that "it is often the most conspicuous and abundant species with the most restricted distributions." He notes that
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wouldn't have directly competed with the disappearing forms anyway. Lehman described the evidence for immigration as a driving force in Lancian dinosaur faunal turnovers as "not particularly compelling."
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to the south. The most spectacular and specialized forms became extinct. The turnover was preceded by an episode of immigration. Associated with the rapid expanse of terrestrial habitat due to melting
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triggered "the most dramatic event that affected Late Cretaceous dinosaur communities in North America prior to their extinction." This turnover event saw specialized and highly ornamented
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association". This association was found to only be present in the later half of the Kirtlandian faunal age, around 73.4–73 million years ago. Another association, this one the "
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Lehman, T. M., 2001, Late Cretaceous dinosaur provinciality: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 310–328.
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Many dinosaur species in North America during the Late Cretaceous had "remarkably small geographic ranges" despite their large body size and high mobility. Large herbivores like
607:. The Fruitland Formation consists entirely of them, and one fifth of all rocks of the Kirtland Formation are a coal. The other common rocks found in the Kirtland Formation are
1174:"The Kirtlandian Land-Vertebrate "Age"-Faunal Composition, Temporal Position, and Biostratigraphic Correlation in the Nonmarine Upper Cretaceous of Western North America"
708:, based on mammal assemblages. Three previously unnamed faunal ages were given names and term "Kirtlandian" was chosen for the gap between the Judithian and Edmontonian.
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are generally regressive throughout the entire sequence the preserved changes in fossil communities represent not only phylogenetic changes but ecological zones from the
368:. However, in the northern biome a general trend in reduction of centrosaurines, with only pachyrhinosaurus surviving. Likewise among lambeosaurs, only the single genus
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is characteristic of southern Alberta. Earlier research had found that lambeosaurines are less common in contemporary Montanan strata and with different centrosaurs as
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also had precursors in North America and its apparent rise to widespreadness may represent the expansion of its preferred habitat rather than an immigration event.
325:. Farther south was characterized by lower taxonomic diversity in communities where lambeosaurines were less common and centrosaurs were completely lacking. There
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association" is found at the very end of the Judithian, right before the Kirtlandian, between 76.5 and 74.2 million years ago. Another association, the "
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is found in both Alaska and upland environments in southern Alberta. Northern and Southern animal biomes approximately correspond respectively with the
35:
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co-occurred in Asia as well as North America. Potential Asian immigrants were especially common in upland environments. The appearance of
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are also present in northern latitudes, so evidently exchange between them occurred, but both are uncommon outside of the southern biome.
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By the Lancian hadrosaurs are no longer the dominant inhabitant of any province of western North America. Lehman records two surviving
65:
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dinosaurs. Just in Montana and Southern Alberta were ten genera of ceratopsians and ten genera of hadrosaurs. An association between
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of the Hunter Wash Member is made up completely of sandstone, which marks the border between the Kirtland and Fruitland formations.
1222:, n. sp. (Theropoda: Dromaeosauridae) From the Upper Cretaceous Kirtland Formation (De-Na-Zin Member), San Juan Basin, New Mexico"
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had already been well documented. Vaguely distinguished inland-versus-coastal dinosaurs had been discussed previously in the
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may have represented an immigration event from South America. Some taxa may have co-occurred on both continents, including
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is well-known, and known with certainty, from the Williams Fork Formation. This means that the formation, along with the
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predominates. The biomes of the Eastern US may have resembled those of Texas except completely lacking in ceratopsians.
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The faunal turnover may be explained by the descent of more primitive forms existing in upland refugia characterized by
873:-dominated flora into areas that were formerly coastal lowlands as the seas retreated and conditions became more arid.
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889:. By contrast, with the mammalian turnovers the newly emerging dominant fauna were clearly old world immigrants, the
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The Kirtlandian is characterized by a single vertebrate association. The association was identified by Lehman in
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The Kirtlandian has four species distinguishing it from other ages. The species include the dinosaurians
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association", was found to date to 70.6 mya, and it used to symbolize the end of the Kirtlandian.
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appears and achieves dominance in its environment very abruptly. Some scientists speculated that
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1196:"The Kirtlandian, A New Land-Vertebrate "Age" for the Late Cretaceous of Western North America"
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1292:. New Mexico Museum of Natural History and Science Bulletin. Vol. 53. pp. 475–483.
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1228:. New Mexico Museum of Natural History and Science Bulletin. Vol. 35. pp. 253–256.
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New Mexico Geological Society Guidebook, 54th Field Conference, Geology of the Zuni Plateau
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As of Lehman's 2001 paper, restrictions in dinosaur occurrences based on distance from the
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is the study of dinosaur geographic distribution, based on evidence in the fossil record.
1180:. New Mexico Museum of Natural History and Science Bulletin. Vol. 35. pp. 7–23.
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association probably represent semi-arid inland plains. In previous research
1067:"Altitudinal and Transcontinental Life Zones," Lehman (2001); pages 312-313.
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be replaced by more primitive upland dinosaurs in the south while northern
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1081:"Altitudinal and Transcontinental Life Zones," Lehman (2001); page 313.
1058:"Altitudinal and Transcontinental Life Zones," Lehman (2001); page 312.
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in 2003 and found by their original study to date from 74.9 to 72
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is also "conspicuous" in the southern biome. Farther south, in Texas,
1398:"Competition from Invaders Hypothesis," Lehman (2001); pages 321-322.
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of the Kirtlandian formations are made up of mostly a combination of
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1407:"Descent from the Highlands Hypothesis," Lehman (2001); page 322.
1389:"Competition from Invaders Hypothesis," Lehman (2001); page 321.
1245:, a giant horned dinosaur from the Late Campanian of New Mexico"
1046:"Endemism Among Herbivorous Dinosaurs," Lehman (2001); page 312.
1028:"Endemism Among Herbivorous Dinosaurs," Lehman (2001); page 311.
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sediments. The rock types within the formations are primarily
18:
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could be explained by immigration from Asia. Dinosaurs like
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occurred as far north as Alaska. "Archaic" elements such as
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association while more coastal areas were characterized by
309:. Inland environments also differed, with the contemporary
255:. Terrestrial sedimentary strata from the Judithian to the
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and the "(re)appearance" of basal neoceratopsians like
1351:"Loss of Wetlands Hypothesis," Lehman (2001); page 320.
1279:"Preliminary Observations on a Skull of the Amiid Fish
1131:"Edmontonian Transition," Lehman (2001); pages 315-317.
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found to date or persist from the Kirtlandian are the
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In the south, little changes in the transition to the
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Late Cretaceous vertebrates from the Western Interior
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Late Cretaceous vertebrates from the Western Interior
1122:"Edmontonian Transition," in Lehman (2001); page 315.
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formations of the basin, are inside the Kirtlandian.
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begin characterizing inland faunas. Lehman described
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Sullivan, R.M.; Jasinski, S.E.; Lucas, S.G. (2011).
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1320:"Lancian Turnover," Lehman (2001); pages 317-319.
1434:"A Recent Analog?" Lehman (2001); pages 323-324.
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814:speculated that a rise in sea level during the
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460:, which lived throughout the Kirtlandian. The
374:remains. Inland faunas are distinguished by a
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1311:"Lancian Turnover," Lehman (2001); page 317.
1113:"Judithian Climax," Lehman (2001); page 315.
343:are the dominant fauna. The giant eusuchian
313:preserving an inland fauna characterized by
217:dinosaurs in the region. Another example is
209:haven't been discovered outside of southern
51:introducing citations to additional sources
1425:"A Recent Analog?" Lehman (2001); page 323.
188:and hadrosaurs exhibited the most obvious
1329:"What Happened?" Lehman (2001); page 319.
1288:. In Sullivan, R.M.; et al. (eds.).
1224:. In Lucas, S.G.; Sullivan, R.M. (eds.).
1176:. In Lucas, S.G.; Sullivan, R.M. (eds.).
41:Relevant discussion may be found on the
1008:"Conclusions," Lehman (2001); page 324.
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213:even though they are the most abundant
192:, which strongly contrasts with modern
678:, with the only non-dinosaurian being
832:resembled Asian forms, and some like
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1194:Sullivan, R.M.; Lucas, S.G. (2003).
1172:Lucas, S.G.; Sullivan, R.M. (2006).
948:"Abstract," Lehman (2001); page 310.
451:in age and is characterized by the
512:. These formations are exposed in
432:The Kirtlandian faunal age of the
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658:, found in the Kirtland Formation
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544:, Baja California, and possibly
34:relies largely or entirely on a
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704:, Judithian, Edmontonian, and
669:Parasaurolophus cyrtocristatus
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1264:10.1016/j.cretres.2010.12.007
319:and the early pachyrhinosaur
121:Late Cretaceous North America
877:single species environments
62:"Dinosaur paleobiogeography"
16:Field of study in archeology
913:A dispersal event near the
223:, the only known Judithian
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1220:Saurornitholestes robustus
926:and the southern biome by
696:land-vertebrate ages, the
562:Bisti/De-Na-Zin Wilderness
506:Cerro del Pueblo Formation
115:Dinosaur paleobiogeography
664:Pentaceratops sternbergii
457:Pentaceratops sternbergii
420:is a likely ancestor for
508:and upper region of the
443:and is succeeded by the
428:Kirtlandian Faunal Stage
1243:Titanoceratops ouranous
1239:Longrich, N.R. (2010).
1216:Sullivan, R.M. (2006).
172:with a greatly reduced
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675:Kritosaurus navajovius
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656:Bistahieversor sealeyi
630:It was first named by
311:Two Medicine Formation
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180:Judithian Faunal Stage
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1504:Dinosaur paleobiology
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816:Bearpaw Transgression
792:and feature abundant
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470:Kaiparowits Formation
462:geological formations
253:scientific literature
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779:and the less common
755:Lancian Faunal Stage
654:Mounted skeleton of
644:Nicholas R. Longrich
303:taking the place of
166:became dominated by
131:Centrosaurus apertus
47:improve this article
1483:Paleontology portal
1252:Cretaceous Research
681:Melvius chauliodous
619:and most commonly,
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566:Ojo Alamo Formation
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632:Robert M. Sullivan
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920:protoceratopsians
829:Nodocephalosaurus
640:million years ago
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510:Aguja Formation
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749:Edmontosaurus
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737:Corythosaurus
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371:Hypacrosaurus
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103:December 2019
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64: –
63:
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58:Find sources:
52:
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36:single source
32:This article
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741:Centrosaurus
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186:ceratopsians
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928:Alamosaurus
924:Triceratops
906:Alamosaurus
854:Alamosaurus
850:Alamosaurus
842:Kritosaurus
838:Alamosaurus
834:Saurolophus
812:Jack Horner
804:Alamosaurus
789:Alamosaurus
765:Triceratops
761:chasmosaurs
729:Kritosaurus
453:ceratopsian
445:Edmontonian
422:Triceratops
377:Saurolophus
366:Edmontonian
359:Kritosaurus
351:Kritosaurus
346:Deinosuchus
328:Kritosaurus
322:Einiosaurus
300:Monoclonius
285:provinces.
279:Normapolles
225:ceratopsian
176:community.
169:Triceratops
1441:References
1205:: 369–377.
915:Cenomanian
820:anagenesis
798:in Texas.
782:Anatotitan
770:Torosaurus
718:Cretaceous
555:Two local
526:New Mexico
434:Cretaceous
261:submontane
229:New Mexico
73:newspapers
934:Footnotes
857:existed.
846:Avisaurus
684:, a fish
625:Bisti Bed
621:sandstone
609:siltstone
605:coal beds
601:lithology
582:siltstone
578:sandstone
574:coal beds
478:Fruitland
449:Campanian
441:Judithian
316:Maiasaura
215:Judithian
194:mammalian
174:hadrosaur
43:talk page
1498:Category
887:glaciars
698:Paluxian
613:mudstone
586:mudstone
546:Coahuila
530:Colorado
502:El Gallo
490:Ringbone
474:Kirtland
447:. It is
190:endemism
1281:Melvius
891:cervids
879:caribou
871:conifer
706:Lancian
702:Aquilan
534:Arizona
518:Montana
514:Alberta
498:Packard
466:Bearpaw
257:Lancian
211:Alberta
87:scholar
895:bovids
672:, and
623:. The
588:, and
557:faunas
548:, and
538:Sonora
500:, and
472:, the
437:period
164:biomes
89:
82:
75:
68:
60:
1286:(PDF)
1248:(PDF)
1199:(PDF)
883:bison
686:taxon
617:shale
590:shale
550:Texas
402:like
227:from
94:JSTOR
80:books
893:and
844:and
767:and
725:2001
634:and
599:The
522:Utah
516:and
390:and
357:and
337:and
293:and
276:and
203:and
158:and
66:news
1260:doi
49:by
1500::
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1256:32
1254:.
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897:.
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101:(
91:·
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39:.
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