Lophorhothon
Encyclopedia
Lophorhothon is a genus
of hadrosauroid dinosaur
from the Late Cretaceous
, the first genus of dinosaur discovered in Alabama
.
dinosaur were first discovered during the 1940s, from extensive erosional outcrops of the lower unnamed member of the Mooreville Chalk Formation
(Selma Group
; lower and middle Campanian
) in Dallas County
, west of the town of Selma, Alabama
. The taxon has since also been reported from Black Creek Formation
(Campanian) of North Carolina
. The holotype
, which is housed in the collections of the Field Museum
in Chicago
, consists of a fragmentary and disarticulated skull and incomplete postcranial skeleton. The length on the holotype specimen has been estimated as 4.5 meters. The genus was named by Wann Langston in 1960. The name Lophorhothon means "crested nose" (Greek
lophos meaning 'crested' and rhothon meaning 'nose'). The type species
is Lophorhothon atopus. The specific name is derived from Greek atopos, "uncommon" or "strange".
. It has been suggested, for example, that the material may actually represent a juvenile Prosaurolophus
. James Lamb in 1998 has suggested the genus may actually represent a basal iguanodont
, an idea that has failed to find widespread acceptance. More recent workers (Horner, Weishampel, and Forster, 2004) have classified Lophorhothon as a basal hadrosaurine and a sister taxon to all other hadrosaurines. An analysis published in 2010 indicated it was a basal member of the Hadrosauroidea
.
sediments of the Mississippi Embayment
.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of hadrosauroid dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
from the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
, the first genus of dinosaur discovered in Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
.
Discovery and naming
Remains of this small, poorly-known perhaps saurolophineHadrosaurid
Hadrosaurids or duck-billed dinosaurs are members of the family Hadrosauridae, and include ornithopods such as Edmontosaurus and Parasaurolophus. They were common herbivores in the Upper Cretaceous Period of what are now Asia, Europe and North America. They are descendants of the Upper...
dinosaur were first discovered during the 1940s, from extensive erosional outcrops of the lower unnamed member of the Mooreville Chalk Formation
Mooreville Chalk Formation
The Mooreville Chalk Formation is a geological formation in North America, within the U.S. states of Alabama and Mississippi. The strata date back to the early Santonian to the early Campanian stage of the Late Cretaceous. The chalk was formed by pelagic sediments deposited along the eastern edge...
(Selma Group
Selma Group
The Selma Group is a geological formation in North America, within the U.S. states of Alabama, Mississippi, and Tennessee. The strata date from the Santonian to the Maastrichtian stages of the Late Cretaceous. The group is composed of, in ascending order, the Mooreville Chalk Formation, Demopolis...
; lower and middle Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
) in Dallas County
Dallas County, Alabama
Dallas County is a county of the U.S. state of Alabama. Its name is in honor of United States Secretary of the Treasury Alexander J. Dallas. The county seat is Selma.- History :...
, west of the town of Selma, Alabama
Selma, Alabama
Selma is a city in and the county seat of Dallas County, Alabama, United States, located on the banks of the Alabama River. The population was 20,512 at the 2000 census....
. The taxon has since also been reported from Black Creek Formation
Black Creek Formation
The Black Creek Formation is a Mesozoic geologic formation. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.-Paleofauna:* Coelosaurus cf antiquus * ?Dryptosaurus sp...
(Campanian) of North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
. The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
, which is housed in the collections of the Field Museum
Field Museum of Natural History
The Field Museum of Natural History is located in Chicago, Illinois, USA. It sits on Lake Shore Drive next to Lake Michigan, part of a scenic complex known as the Museum Campus Chicago...
in Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
, consists of a fragmentary and disarticulated skull and incomplete postcranial skeleton. The length on the holotype specimen has been estimated as 4.5 meters. The genus was named by Wann Langston in 1960. The name Lophorhothon means "crested nose" (Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
lophos meaning 'crested' and rhothon meaning 'nose'). The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
is Lophorhothon atopus. The specific name is derived from Greek atopos, "uncommon" or "strange".
Taxonomic status
Over the forty-six years since the publication of Langston's description of Lophorhothon a number of workers have questioned the validity of this genusGenus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
. It has been suggested, for example, that the material may actually represent a juvenile Prosaurolophus
Prosaurolophus
Prosaurolophus is a genus of hadrosaurid dinosaur from the Late Cretaceous of North America. It is known from the remains of at least 25 individuals belonging to two species, including skulls and skeletons, but it remains obscure...
. James Lamb in 1998 has suggested the genus may actually represent a basal iguanodont
Iguanodont
Iguanodonts were herbivorous dinosaurs that lived from the mid-Jurassic to Late Cretaceous. Some members include Camptosaurus, Callovosaurus, Iguanodon, Ouranosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodonts were one of the first groups of dinosaurs to be found...
, an idea that has failed to find widespread acceptance. More recent workers (Horner, Weishampel, and Forster, 2004) have classified Lophorhothon as a basal hadrosaurine and a sister taxon to all other hadrosaurines. An analysis published in 2010 indicated it was a basal member of the Hadrosauroidea
Hadrosauroidea
Hadrosauroidea is a clade or superfamily of ornithischian dinosaurs that includes the "duck-billed" dinosaurs, or hadrosaurids, and their close relatives. Many primitive hadrosauroids, such as the sail-backed Ouranosaurus, have traditionally been included in a paraphyletic "Iguanodontidae"...
.
Holotype
The specimen which Langston designated as the holotype was discovered by Rainier Zangerl, Bill Turnbull and Charles Barber on a Field Museum expedition in 1946 and was given catalogue number FMNH P 27383. It consists of less than one half of the skull, a number of vertebrae, and significant portions of the fore- and hindlimbs. Preserved cranial material includes a partial quadrate, left maxilla, teeth, jugal, lacrimal, nasal (with the namesake crest), postorbital, frontal, prefrontal, parietal, squamosal, and paroccipital process and a portion of the predentary bone. The specimen was likely washed out to sea by a river, where it eventually sank and was buried in the silty carbonateCarbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
sediments of the Mississippi Embayment
Mississippi embayment
The Mississippi Embayment is a physiographic feature in the south-central United States, part of the Mississippi Alluvial Plain. It is essentially a northward continuation of the fluvial sediments of the Mississippi River Delta to its confluence with the Ohio River at Cairo, Illinois. The embayment...
.