Smoky Hill Chalk

The Smoky Hill Chalk Member of the Niobrara Chalk formation is a Cretaceous conservation Lagerstätte, or fossil rich geological formation, known primarily for its exceptionally well-preserved marine reptiles.[1] The Smoky Hill Chalk Member is the uppermost of the two structural units of the Niobrara Chalk.[1] It is underlain by the Fort Hays Limestone Member; and the Pierre Shale overlies the Smoky Hill Chalk.[1] The Smoky Hill Chalk outcrops in parts of northwest Kansas, its most famous localities for fossils, and in southeastern Nebraska. Large well-known fossils excavated from the Smoky Hill Chalk include marine reptiles such as plesiosaurs, large bony fish such as Xiphactinus, mosasaurs, flying reptiles or pterosaurs (namely Pteranodon), flightless marine birds such as Hesperornis, and turtles. Many of the most well-known specimens of the marine reptiles were collected by dinosaur hunter Charles H. Sternberg and his son George. The son collected a unique fossil of the giant bony fish Xiphactinus audax with the skeleton of another bony fish, Gillicus arcuatus inside the larger one. Another excellent skeleton of Xiphactinus audax was collected by Edward Drinker Cope during the late nineteenth century heyday of American paleontology and its Bone Wars.[2]

Smoky Hill Chalk
Stratigraphic range: Late Coniacian-Early Campanian
Toxochelys
This fossil of Prionochelys, an extinct marine turtle, is held in the Smithsonian's National Museum of Natural History. Many Smoky Hill Chalk vertebrate fossils have found their ways to natural history museums all over the world.
TypeGeological formation
Unit ofNiobrara Formation
Lithology
PrimaryChalk
Location
Regionmid-continental
Country United States
Type section
Named forSmoky Hills, Kansas

References

  1. ^ a b c Bottjer, David J.; Etter, Walter; Hagadorn, James W.; et al., eds. (2002). Exceptional Fossil Preservation: A unique View on the Evolution of Marine Life. Columbia University Press. ISBN 0-231-10255-0.
  2. ^ Schwimmer, David R. (2002). King of the Crocodylians: The Paleobiology of Deinosuchus. Indiana University Press. ISBN 0-253-34087-X.

External links

Apatornis

Apatornis is a genus of prehistoric birds endemic to North America during the late Cretaceous. It currently contains a single species, Apatornis celer, which lived around the Santonian-Campanian boundary, dated to about 83.5 million years ago. The remains of this species were found in the Smoky Hill Chalk of the Niobrara Formation in Kansas, United States. It is known from a single fossil specimen: a synsacrum, the fused series of vertebrae over the hips.

While the known fossil remains are very incomplete, enough has been found to reasonably estimate that the body length of this bird was between 7–8 inches (18–20 cm).The type specimen of A. celer, YPM 1451, was reportedly discovered by Othniel Charles Marsh in October 1872 at Butte Creek in Logan County, Kansas. This location is now recognized as falling between Marker Units 15 and 19 of the Smoky Hill Chalk geological formation. An additional, more complete specimen had also been referred to Apatornis celer by Marsh. This more complete specimen had historically been the one used almost exclusively to form the basis of what was known about Apatornis. However, Julia Clarke noted in 2004 that because the second specimen did not preserve any of the same bones as the first, the two could not be scientifically compared. Clarke therefore reclassified the second specimen as its own genus and species, Iaceornis marshi.

Appalachia (Mesozoic)

In the Mesozoic era (252 to 66 million years ago), most during the Late Cretaceous (100.5 to 66 million years ago) Appalachia, named for the Appalachian Mountains, was an island land mass separated from Laramidia to the west by the Western Interior Seaway. This seaway had split North America into two massive landmasses due to a multitude of factors such as tectonism, changes in sea level, and sea-level fluctuations for nearly 40 million years. seaway eventually exapanded, divided across the Dakotas, and by the end of the Cretaceous, it retreated towards the Gulf of Mexico and the Hudson Bay. This left the island masses joined in the continent of North America as the Rocky Mountains rose. From the Cenomanian to the end of the Campanian ages of the Late Cretaceous, Appalachia was separated from the rest of North America. As the Western Interior Seaway retreated in the Maastrichtian, Laramidia and Appalachia eventually connected. Because of this, its fauna was isolated, and developed very differently from the tyrannosaur, ceratopsian, pachycephalosaur and ankylosaur dominated fauna of the western part of North America, known as "Laramidia".Due to numerous lesser explored fossiliferous deposits and due the fact that half of Appalachia's fossil formations, mostly in the northern region, being destroyed by the Pleistocene ice age, little is known about Appalachia, with exception of plant life, marine life and the insects trapped in amber from New Jersey. Many of the various fossil formations not destroyed by the Pleistocene ice age still remain elusive to the field of paleontological study. In addition, due to a lack of interest in Appalachia, many fossils that have been found in Appalachia lie unstudied and remain in the inaccurate genera to which they were assigned in the days of E. D. Cope and O. C. Marsh. Only a few fossils of the terrestrial creatures that were found in this region have given us a brief glimpse into what life was like here during the Cretaceous period. However, the area has seen a bit of a resurgence of interest due to several discoveries made in the past few years. As mentioned earlier, not much is known about Appalachia, but some fossil sites, such as the Woodbine Formation, Navesink Formation, Ellisdale Fossil Site, Mooreville Chalk Formation, Demopolis Chalk Formation, Black Creek Group and the Niobrara Formation, together with ongoing research in the area, have given us a better look into this forgotten world of paleontology.

Concretion

A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular shapes also occur. The word 'concretion' is derived from the Latin con meaning 'together' and crescere meaning 'to grow'. Concretions form within layers of sedimentary strata that have already been deposited. They usually form early in the burial history of the sediment, before the rest of the sediment is hardened into rock. This concretionary cement often makes the concretion harder and more resistant to weathering than the host stratum.

There is an important distinction to draw between concretions and nodules. Concretions are formed from mineral precipitation around some kind of nucleus while a nodule is a replacement body.

Descriptions dating from the 18th century attest to the fact that concretions have long been regarded as geological curiosities. Because of the variety of unusual shapes, sizes and compositions, concretions have been interpreted to be dinosaur eggs, animal and plant fossils (called pseudofossils), extraterrestrial debris or human artifacts.

Dawndraco

Dawndraco is a controversial genus of pteranodontid pterosaur from the Late Cretaceous of North America. It is likely synonymous with the contemporary pteranodontid Pteranodon sternbergi.

'Dawndraco' was named by Alexander W.A. Kellner in 2010. The type species is Dawndraco kanzai. The generic name combines the Dawn deity of the Iroquois with a Latin draco, "dragon". The specific name refers to the Kanza tribe of Kansas.'Dawndraco' is based on the holotype specimen UALVP 24238, a partial skeleton including an almost complete skull and lower jaws. It was recovered in 1974 by Richard C. Fox and Allen Lindoe from rocks of the lower part of the Smoky Hill Chalk Member of the Niobrara Formation in Utica, Kansas. These rocks date to the late Coniacian or early Santonian stage, about 86 million years ago.

The specimen was earlier referred to Pteranodon sternbergi. However, when Kellner in 2010 assigned this latter species to the genus Geosternbergia, he concluded that specimen UALVP 24238 was too different from it to be accounted for by individual variation or sexual dimorphism and therefore named a separate genus. A unique trait is that the snout does not strongly taper anteriorly as with Pteranodon, the upper and lower margins running almost parallel instead. Kellner further argued that the provenance of the specimen - from rock units between those of other Pteranodon holotypes - supported his interpretation of morphological differences as being taxonomic in nature, rather than relating to growth or gender. 'Dawndraco' was assigned by Kellner to the Pteranodontidae.

In a detailed description and discussion of UALVP 24238, Martin-Silverstone et al. (2017) concluded that 'D. kanzai' was not a distinct genus or species from Pteranodon. They showed that its taxonomic characterisations were suspect or erroneous, and that stratigraphic arguments used to further distinguish 'D. kanzai' from other pteranodontids were questionable when compared to the geologic ranges of other Smoky Hill Chalk species. They concluded that UALVP 24238 is better interpreted as a small (not fully osteologically mature) individual of the larger size-class (male) of Pteranodon sternbergi. Their interpretation echoes sceptism expressed about the 2010 Pteranodon revision from other palaeontologists, several of whom have continued to use pre-2010 taxonomies when discussing the Smoky Hill Chalk pteranodonts. In 2014, Andres, Clark, and Xu stated that they would continue to follow the pre-2010 taxonomy of pteranodontids, and referred the new species named by Kellner, including Dawndraco, back to their original classifications following Bennett.

Dolichorhynchops

Dolichorhynchops is an extinct genus of polycotylid plesiosaur from the Late Cretaceous (early Turonian to late Campanian stage) of North America, containing three species, D. osborni, D. bonneri and D. tropicensis, as well as a questionably referred fourth species, D. herschelensis. Dolichorhynchops was an oceangoing prehistoric reptile. Its Greek generic name means "long-nosed face".

Fumicollis

Fumicollis is a genus of prehistoric flightless birds from the Late Cretaceous (Coniacian-Santonian) Niobrara Chalk of Kansas.

Geosternbergia

Geosternbergia is an extinct pteranodontid reptile from the Late Cretaceous geological period of North America. It was one of the largest pterosaur genera and had a wingspan of up to 7.25 metres (23.8 ft).

Hesperornis

Hesperornis (meaning "western bird") is a genus of penguin-like bird that spanned the first half of the Campanian age of the Late Cretaceous period (83.5–78 mya). One of the lesser-known discoveries of the paleontologist O. C. Marsh in the late 19th century Bone Wars, it was an early find in the history of avian paleontology. Locations for Hesperornis fossils include the Late Cretaceous marine limestones from Kansas and the marine shales from Canada. Nine species are recognised, eight of which have been recovered from rocks in North America and one from Russia.

Hierosaurus

Hierosaurus (meaning "sacred lizard") is an extinct genus of nodosaurid ankylosaur which lived during the Cretaceous 87 to 82 million years ago. Its fossils were found in the Smoky Hill Chalk Member of the Niobrara Formation, in western Kansas, which would have been near the middle of Western Interior Sea during the Late Cretaceous. It was a nodosaurid, an ankylosaur without a clubbed tail.

The only species of this genus, Hierosaurus sternbergii, was described by George Wieland on the basis of cranial and postcranial osteoderms collected by Charles Hazelius Sternberg in the Niobrara Formation of western Kansas. Nowadays, Hierosaurus is considered a nomen dubium, and a second species, H. coleii, was reassigned to the new genus Niobrarasaurus in 1995.

List of fossiliferous stratigraphic units in Kansas

This article contains a list of fossil-bearing stratigraphic units in the state of Kansas, U.S.

Niobrara Formation

The Niobrara Formation , also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is composed of two structural units, the Smoky Hill Chalk Member overlying the Fort Hays Limestone Member. The chalk formed from the accumulation of coccoliths from microorganisms living in what was once the Western Interior Seaway, an inland sea that divided the continent of North America during much of the Cretaceous. It underlies much of the Great Plains of the US and Canada. Evidence of vertebrate life is common throughout the formation and includes specimens of plesiosaurs, mosasaurs, and pterosaurs as well as several primitive aquatic birds. The type locality for the Niobrara Chalk is Knox County in northeastern Nebraska.

Niobrarasaurus

Niobrarasaurus (meaning "Niobrara lizard") is an extinct genus of nodosaurid ankylosaur which lived during the Cretaceous 87 to 82 million years ago. Its fossils were found in the Smoky Hill Chalk Member of the Niobrara Formation, in western Kansas, which would have been near the middle of Western Interior Sea during the Late Cretaceous. It was a nodosaurid, an ankylosaur without a clubbed tail. It was closely related to Nodosaurus.

The type species, Niobrarasaurus coleii, was discovered and collected in 1930 by a geologist named Virgil Cole. It was originally described by Mehl in 1936 and named Hierosaurus coleii. It was then re-described as a new genus by Carpenter et al. in 1995. In 2002 the type specimen was transferred to the Sternberg Museum of Natural History, Hays, Kansas.

Paleobiota of the Niobrara Formation

During the time of the deposition of the Niobrara Chalk, much life inhabited the seas of the Western Interior Seaway. By this time in the Late Cretaceous many new lifeforms appeared such as mosasaurs, which were to be some of the last of the aquatic lifeforms to evolve before the end of the Mesozoic. Life of the Niobrara Chalk is comparable to that of the Dakota Formation, although the Dakota Formation, which was deposited during the Cenomanian, predates the chalk by about 10 million years.

Platecarpus

Platecarpus ("flat wrist") is an extinct genus of aquatic lizards belonging to the mosasaur family, living around 84–81 million years ago during the middle Santonian to early Campanian, of the Late Cretaceous period. Fossils have been found in the United States and a possible specimen in Belgium and Africa. A well-preserved specimen of Platecarpus shows that it fed on moderate-sized fish, and it has been hypothesized to have fed on squid, and ammonites as well. Like other mosasaurs, it was initially thought to have swum in an eel-like fashion, although another study suggests that it swam more like modern sharks. An exceptionally well-preserved specimen of P. tympaniticus known as LACM 128319 shows skin impressions, pigments around the nostrils, bronchial tubes, and the presence of a high-profile tail fluke, showing that it and other mosasaurs did not necessarily have an eel-like swimming method, but were more powerful, fast swimmers. It is held in the Natural History Museum of Los Angeles County.

Platyceramus

Platyceramus was a genus of Cretaceous bivalve molluscs belonging to the extinct inoceramid lineage. It is sometimes classified as a subgenus of Inoceramus.

Protostega

Protostega ('first roof') is an extinct genus of sea turtle containing a single species, Protostega gigas. Its fossil remains have been found in the Smoky Hill Chalk formation of western Kansas (Hesperornis zone, dated to 83.5 million years ago) and time-equivalent beds of the Mooreville Chalk Formation of Alabama. Fossil specimens of this species were first collected in 1871, and named by Edward Drinker Cope in 1872. With a length of 3 metres (9.8 ft), it is the second-largest sea turtle that ever lived, second only to the giant Archelon, and the third-largest turtle of all time behind Archelon and Stupendemys.

Smoky Hills

The Smoky Hills are an upland region of hills in the central Great Plains of North America. They are located in the Midwestern United States, encompassing north-central Kansas and a small portion of south-central Nebraska.

The hills are a dissected plain covered by tallgrass and mixed-grass prairie. The Smoky Hills were formed by sedimentary deposits during the Cretaceous period and consist of chalk, limestone, and sandstone rock outcroppings.

Toxochelys

Toxochelys (TOKS uh KEE leez) is an extinct genus of marine turtle from the Late Cretaceous period. It is the most commonly found fossilized turtle species in the Smoky Hill Chalk, in western Kansas.

Tylosaurus

Tylosaurus (Greek τυλος/tylos "protuberance, knob" + Greek σαυρος/sauros "lizard") was a mosasaur, a large, predatory marine reptile closely related to modern monitor lizards and to snakes, from the Late Cretaceous.

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