''Protohadros'' (meaning "first hadrosaur") is a genus of herbivorous ornithischian dinosaur from the Late Cretaceous (

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

stage). Gary Byrd, a part-time palaeontologist, discovered some remains of this euornithopod (ribs and an ungual) during early 1994 at

Flower Mound Flower Mound is an incorporated town located in Denton and Tarrant counties in the U.S. state of Texas. Located northwest of Dallas and northeast of Fort Worth adjacent to Grapevine Lake, the town derives its name from a prominent mound locat ...

, Denton County, north-central Texas. He informed professional palaeontologist Yuong-Nam Lee of the find, who arranged for the entire preserved fossil to be excavated. It was first reported upon in 1996 by Jason Head of the

Dedman College of Humanities and Sciences Dedman College of Humanities and Sciences is the school of liberal arts at Southern Methodist University in Dallas, Texas Dallas () is the third largest city in Texas and the largest city in the Dallas–Fort Worth metroplex, the fourth- ...

, Southern Methodist University. The type species ''Protohadros byrdi'' was described and named by Head in 1998. The genus name is derived from Greek πρῶτος, ''protos'', "first", en ἁδρός, ''hadros'', "thick", a reference to the fact that Head considered the species the oldest known hadrosaur. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

honours Byrd. The holotype, specimen SMU 74582, of ''Protohadros'', was found in the

Woodbine Formation The Woodbine Group is a geological formation in east Texas whose strata date back to the Early to Middle Cenomanian age of the Late Cretaceous. It is the producing formation of the giant East Texas Oil Field (also known as the "Black Giant") from ...

, which dates to the middle

. It consists of a partial skull, pieces of ribs, a hand ungual and a neural arch. In 1997 Lee named possible tracks of ''Protohadros'' as the ichnospecies ''

Caririchnium ''Caririchnium'' is an ichnogenus of ornithopod dinosaur footprint, belonging to either derived iguanodonts or basal hadrosauroids. It includes the species ''Caririchnium lotus'' from Lower Cretaceous Jiaguan Formation and ''C''. ''protohadrosau ...

protohadrosaurichnos''.Yuong-Nam Lee, 1997, "Bird and dinosaur footprints in the Woodbine Formation (Cenomanian), Texas", ''Cretaceous Research'' (1997) 18: 849-864 Due to the paucity of the remains much of the reconstruction of this dinosaur is speculative. The skull is about seventy centimetres long. From this Head estimated the length of the type specimen of ''Protohadros'' at seven to eight metres. He pointed out that this specimen was that of a subadult and that fully-grown individuals could have been longer. ''Protohadros'' had a massive, very deep set of lower jaws, and the snout was strongly turned down at the front, which according to Head suggested a habit of grazing on low-growing plants, rather than browsing from bushes or overhanging branches. Its diet would then have consisted of the swamp plants which grew in the delta streams in its habitat, scooped up by the broad, down-turned mouth. In some respects ''Protohadros'' was intermediate in morphology to more derived hadrosaurids. Like these it did have

pleurokinesis Cranial kinesis is the term for significant movement of skull bones relative to each other in addition to movement at the joint between the upper and lower jaw. It is usually taken to mean relative movement between the upper jaw and the braincase. ...

, a cranial joint system that produced the food-grinding action, but only partially in that the

quadrate Quadrate may refer to: * Quadrate bone * Quadrate (heraldry) * Quadrate lobe of liver * Quadrate tubercle The quadrate tubercle is a small tubercle found upon the upper part of the femur. It serves as a point of insertion of the quadratus femori ...

at the back of the skull was still relatively immobile. ''Protohadros'' rear legs were probably longer than the front pair, and it could move on all fours or walk and run on its hind legs only. ''Protohadros'' was first described as the most

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

member of the

Hadrosauridae Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which includ ...

, hence its generic name. However, scientific opinion has since changed and it is now regarded as a non-hadrosaurid iguanodontian, a basal member of the Hadrosauroidea, though one closely related to the Hadrosauridae. The dinosaur's discovery conflicted with the idea that hadrosaurids evolved in Asia, but its reassessment as a less-

derived Derive may refer to: * Derive (computer algebra system), a commercial system made by Texas Instruments * ''Dérive'' (magazine), an Austrian science magazine on urbanism *Dérive, a psychogeographical concept See also * *Derivation (disambiguatio ...

iguanodontian has rendered this discrepancy less problematic.

References

External links

''Protohadros'' in the Dino Directory
{{Taxonbar, from= Q1976657, from2= Q3924310 Iguanodonts Late Cretaceous dinosaurs of North America Fossil taxa described in 1998 Paleontology in Texas