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29-710: In 1913 , a US Geological Survey crew headed by Eugene Stebinger and a US National Museum crew headed by Charles Gilmore worked together to excavate the first dinosaur of the formation. Stebinger was the first to identify the Two Medicine Formation and formally described the first fossils in a scientific paper published in 1914 . Gilmore returned to the Formation in 1928 and 1935 . During this time frame only three species were named and of these only Styracosaurus ovatus and Edmontonia rugosidens are still regarded as valid. Barnum Brown prospected

58-483: A large mass of forested lava associated with the batholith. The batholith is composed of at least seven, and possibly as many as 14, discrete rock masses called plutons , which had formed beneath the Earth's surface during a period of magma intrusion about 73 to 78 million years ago ( Late Cretaceous time). The rising buoyant plutons resulted from subduction along what was then the west coast of North America, which

87-1358: A long history both before and after becoming formalized as a science . This article records significant discoveries and events related to paleontology that occurred or were published in the year 1913. Leucotermes robustus sp. nov Synonym von Rosen Lutetian Baltic amber [REDACTED]   Europe A Stylotermitid termite. synonym of Parastylotermes robustus Protosmylus picta Gen et comb. nov Synonym (Hagen) Priabonian Baltic amber [REDACTED]   Europe A protosmyline Osmylid lance lacewing Moved from " Osmylus " picta ( 1856 ) moved to Osmylidia picta ( 2021 ) Diictodon Valid Robert Broom Middle Permian Pristerognathus zone A dicynodont belonging to Pylaecephalidae , living in burrows. Eocyclops Junior synonym Robert Broom Late Permian Junior synonym of Rhachiocephalus . Ictidorhinus Valid Broom Late Permian Dicynodon assemblage zone A biarmosuchian . Scylacops Valid Broom Late Permian Cistecephalus assemblage zone A member of Gorgonopsia . Valid A geosaurine metriorhynchid . Leurospondylus Valid Brown Ogmodirus Valid Williston Moodie Data courtesy of George Olshevsky's dinosaur genera list. Boulder Batholith The Boulder Batholith

116-538: A non-azhdarchid azhdarchoid. Insect and mammal burrows have also been discovered, as well as dinosaur coprolites . 1913 in paleontology Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils . This includes the study of body fossils, tracks ( ichnites ), burrows , cast-off parts, fossilised feces ( coprolites ), palynomorphs and chemical residues . Because humans have encountered fossils for millennia, paleontology has

145-549: Is a relatively small batholith in southwestern Montana , United States, exposed at the surface as granite (more specifically quartz monzonite ) and serving as the host rock for rich mineralized deposits at Butte and other locations. The batholith lies roughly between Butte and Helena , and between the Deer Lodge (Upper Clark Fork) Valley and the Broadwater (Upper Missouri) Valley. The volcanic Elkhorn Mountains are

174-619: Is common in the Two Medicine. To the south extrusive volcanic activity occurred in association with the Boulder Batholith collectively called the Elkhorn Volcanics . Most of the vertebrate fossils are preserved by CaCo 3 permineralization . This type of preservation preserves high levels of detail, even down to the microscopic level. However, it also leaves specimens vulnerable to weathering when exposed to

203-771: The Canada–United States border , the Two Medicine Formation correlates to the Belly River Group in southwest Alberta, and the Pakowki Formation eastward. The Two Medicine overlies the Virgelle Sandstone , which formed from the beach sands exposed on northern and western shores of the receding Colorado Sea . A Cretaceous Interior Seaway transgression submerged the area briefly early on in Two Medicine history leaving anomalous paralic sediments and isolated shale bodies about 100 m above

232-741: The Horsethief represent shallower water deposits than the Bearpaw Shale adding further evidence of higher elevation areas existing in the south. Egg Mountain, which is near Choteau, Montana , was discovered in 1977 by Marion Brandvold, owner of the Trex Agate Rock Shop in Bynum, Montana , who discovered the bones of juvenile dinosaurs at this site. It is a colonial nesting site on the Willow Creek Anticline in

261-699: The Late Cretaceous western margin of North America. Later hydrothermal vein activity along fault and shear zones within the Butte quartz monzonite and its contact with adjacent rocks, resulted in major ore deposits of lead, zinc, and silver. The Boulder Batholith was named for the prominent rounded boulders that typify its landscape, the result of spheroidal weathering of fractured granite. It measures approximately 75 miles (121 km) north-south by about 25 miles (40 km) east-west, rather small in comparison to most batholiths. This article about

290-460: The Two Medicine Formation that is famous for its fossil eggs of Maiasaura , which demonstrated for the first time that at least some dinosaurs cared for their young. The eggs were arranged in dug-out earthen nests, each nest about a parent's body length from the next, and baby dinosaurs were also found with skeletons too cartilaginous for them to walk - similar to those of altricial (helpless) baby birds . The parent(s) must then have brought food to

319-487: The Two Medicine Formation would have the same dinosaurs as the Judith River Formation. It was only in 1978, that it was discovered that the formation had endemic dinosaurs. Even some genera regarded as wide-ranging predators exhibited a species difference between the Two Medicine and other formations. No ecological barriers have been postulated apart from upland/lowland habitat preference differences between

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348-627: The Two Medicine Formation. The Two Medicine Formation spans from 82.4 to 74.4 Ma, nearly the entire length of the Campanian stage. There are several equivalents to the Two Medicine Formation, as with many geologic formations (most of which are named after their type locality ). The Sweetgrass Arch in Montana divides the Two Medicine from the Judith River Formation , Bearpaw Shale , Claggett Shale , and Eagle Sandstone . Across

377-471: The Two Medicine and Judith River Formation. There is no unequivocal evidence for intermingling between the wildlife of the Two Medicine and geographically adjacent contemporary formations. Dinosaur remains are more common in the upper part of the Two Medicine. An unidentified lambeosaurine has been collected from the same stratigraphic placement, west of Bynum, and is in preparation at The Montana Dinosaur Center The first find of an oviraptorosaur in Montana

406-451: The apparent diversification was a real event rather than a result of preservational biases. The timeline below follows the stratigraphic chart presented by Horner et al. 2001. Some of the dinosaurs from the formation have been speculated to show signs of drought related death. Very few articulated dinosaurs have been found in the formation; most specimens are isolated, bone bed, poorly preserved or broken remains. Early studies assumed that

435-541: The base of the formation. The Middle portion of the two medicine formation is about 225 m thick, deposited while the Clagette Sea was receding and the Bearpaw Sea transgressing. This portion is stratigraphically equivalent to the Judith River Formation and Judith River Group . The sediments are mainly bentonitic siltstones and mudstones with "occasional sandstone lenses." These sediments are thought to be

464-472: The bulk of the batholith (about 70%), with additional named intrusions along the periphery consisting of granodiorite , monzogranite , and minor syenogranite . The batholith intruded into Mesoproterozoic and Mesozoic sedimentary rocks , including the Elkhorn Mountains volcanics . The origin of these igneous rocks is related to subduction and continental magmatic arc processes associated with

493-524: The dinosaurs from the formation have been speculated to have shown signs of drought-related death. A more upland environment existed in the south of the Two Medicine Formation. Streams had a northeasterly flow away from these southwestern uplands. The southern part of the Two medicine formation grades into brackish water siltstone/sandstone series called the Horsethief Formation . The sediments of

522-492: The formation and many new kinds of dinosaurs were discovered. More nesting sites were discovered later, including the Devil's Coulee site yielding Hypacrosaurus stebingeri in southern Alberta in 1987 . The loosely consolidated fine grain sediments composing the formation allow for fast plant growth in badland areas, limiting the number of exposed outcrops. Paleosols , fluvial deposits and bentonitic layers are common in

551-401: The formation in 1933 , but found nothing significant. Both of their research were interrupted by World War II . In 1977 , Trexler reports finding hadrosaur remains west of Choteau, Montana . During the next year baby hadrosaurs were discovered. In 1979 , Horner and Makela referred these hadrosaur bones to Maiasaura peeblesorum . The announcement attracted renewed scientific interest to

580-400: The formation is more diverse and preserves better quality fossils. However, many of the taxa that supposedly distinguished it as a separate fauna have since been found in older sediments. In particular, Gryposaurus latidens and Hypacrosaurus have been found to coexist with Maiasaura . Further, there are fossil teeth that seem to show the presence of certain taxa are unbroken throughout

609-433: The formation's stratigraphic column. Usually the lower sediments of a given formation will contain the same kinds of dinosaurs as the upper sediments, or the species composition changes only gradually. However, some researchers had argued that the Two Medicine Formation was an exception, preserving multiple distinct dinosaur faunas. Later research came to find that the supposedly distinct dinosaur faunas at different levels of

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638-459: The formations were more similar than had been previously thought. While the dinosaur fauna of the lower and middle sections Two Medicine was apparently diverse, the quality of preservation was low and few of these remains can be referred to individual species. The middle Two Medicine is a better source of fossils, but still poor overall. This makes it difficult to argue that these sections of the formation preserve distinct faunas. The upper portion of

667-547: The remains of a coastal plain "far removed" from the interior sea. The upper portion is about one half of the formation. Its sediments are similar to the middle portions but punctuated by extensive red beds and caliche horizons. The uppermost 80 m were deposited after the inundation of the Judith River equivalent sediments by the Bearpaw Sea. They are thought to have been deposited in only 500,000 years. Bentonitic ash

696-580: The surface. The Two Medicine Formation was deposited in a seasonal, semi-arid climate with possible rainshadows from the Cordilleran highlands. This region during the Campanian experienced a long dry season and warm temperatures. Lithologies, invertebrate faunas, and plant and pollen data support the above interpretation. The extensive red beds and caliche horizons of the upper Two Medicine are evidence of at least seasonally arid conditions. Some of

725-552: The whole formation. Nevertheless, some true changes in faunal composition seem to occur in the upper Two Medicine. The appearance of Maiasaura in the formation precedes the arrival of a diverse variety of other ornithischians. According to David Trexler, thorough examination of strata found along the Two Medicine River (which exposes the entire upper half of the Two Medicine Formation) indicates that

754-402: The young, and there is plant matter in the nests that may be evidence of either this or for incubation of the eggs. Maiasaura also grew extremely fast, at rates comparable to modern birds. Skeletons of Orodromeus and skeletons and eggs of Troodon were also found at Egg Mountain. Most dinosaur-bearing rock formations do not contain multiple distinct faunas at different positions within

783-740: Was an articular region from the lower jaw of Caenagnathus sternbergi , from the Two Medicine Formation, according to a 2001 paper by David J. Varrichio . This species had previously only been known from the Canadian province of Alberta . Varricchio observes that during the late Campanian , Alberta and Montana had very similar theropods despite significant differences in the types of herbivorous dinosaur faunas. Many other fossil animals have been found, such as freshwater bivalves , gastropods , turtles , lizards such as Magnuviator , and champsosaurs . The multituberculate mammal Cimexomys has been found on Egg Mountain. The species Piksi barbarulna

812-428: Was described based on forelimb bones from the Two Medicine Formation; it was initially thought to be a bird , but subsequently it was reinterpreted as a pterosaur , likely a member of Ornithocheiroidea . Azhdarchoid pterosaurs are also known from the Two Medicine Formation, including a very large, yet-unnamed azhdarchid , the estimated wingspan of which was 8 metres (26 ft), and smaller Montanazhdarcho minor ,

841-400: Was near today's border between Montana and Idaho . Regional uplift brought the deep-seated granite to the surface, where erosion exposed the rocks and the extremely rich mineral veins they contained. Hundreds of millions of dollars of copper, silver, gold, zinc, lead, and other metals have been mined from the batholith, both using underground mining and pit mining. The Butte Granite makes up

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