Microhadrosaurus
Encyclopedia
Microhadrosaurus is a genus
of duckbill dinosaur
from the Campanian
or Maastrichtian
-age Upper Cretaceous Yuanpu Formation (also known as the Nanxiong Formation) of Guangdong
, China
. Although its name identifies it as a small duckbill, it is based on juvenile
remains, and the size of the adult hadrosaur is unknown.
named this genus for IVPP V4732
, a partial lower jaw from a juvenile hadrosaur. This partial bone, with 18 columns of stacked teeth
in a typical hadrosaur tooth battery, measures 37 centimeters long (15 inches). Dong later estimated the length of the individual at 2.6 meters (8.5 feet).
, albeit in tiny form. However, Michael K. Brett-Surman, a hadrosaur specialist, regarded the material as showing no characteristics that would allow it to be differentiated from other duckbills. The most recent review accepts Brett-Surman's position, and regards Microhadrosaurus as a dubious
name.
al herbivore
, eating plant
s with a sophisticated skull that permitted a grinding motion analogous to chewing
, and was furnished with hundreds of continually-replaced teeth. Because it is only known from a partial jaw from a juvenile, little more than general information can be drawn from it at this point.
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 duckbill 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 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 ...
or Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
-age Upper Cretaceous Yuanpu Formation (also known as the Nanxiong Formation) of Guangdong
Guangdong
Guangdong is a province on the South China Sea coast of the People's Republic of China. The province was previously often written with the alternative English name Kwangtung Province...
, China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
. Although its name identifies it as a small duckbill, it is based on juvenile
Juvenile (organism)
A juvenile is an individual organism that has not yet reached its adult form, sexual maturity or size. Juveniles sometimes look very different from the adult form, particularly in terms of their colour...
remains, and the size of the adult hadrosaur is unknown.
Description
Dong ZhimingDong Zhiming
Dong Zhiming , from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, is one of China's leading paleontologists. He began working at the IVPP in 1962, learning from Yang Zhongjian who was director at the time...
named this genus for IVPP V4732
Institute of Vertebrate Paleontology and Paleoanthropology
The Institute of Vertebrate Paleontology and Paleoanthropology of China is a prominent research institution and collections repository for fossils, including many dinosaur and pterosaurand cat poo specimens...
, a partial lower jaw from a juvenile hadrosaur. This partial bone, with 18 columns of stacked teeth
Tooth
Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...
in a typical hadrosaur tooth battery, measures 37 centimeters long (15 inches). Dong later estimated the length of the individual at 2.6 meters (8.5 feet).
History
Dong regarded this genus as much like EdmontosaurusEdmontosaurus
Edmontosaurus is a genus of crestless hadrosaurid dinosaur. It contains two species: Edmontosaurus regalis and Edmontosaurus annectens. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian stage of the Cretaceous Period 73 million years ago,...
, albeit in tiny form. However, Michael K. Brett-Surman, a hadrosaur specialist, regarded the material as showing no characteristics that would allow it to be differentiated from other duckbills. The most recent review accepts Brett-Surman's position, and regards Microhadrosaurus as a dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
name.
Paleobiology
As a hadrosaurid, Microhadrosaurus would have been a bipedal/quadrupedQuadruped
Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...
al herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
, eating plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s with a sophisticated skull that permitted a grinding motion analogous to chewing
Mastication
Mastication or chewing is the process by which food is crushed and ground by teeth. It is the first step of digestion and it increases the surface area of foods to allow more efficient break down by enzymes. During the mastication process, the food is positioned between the teeth for grinding by...
, and was furnished with hundreds of continually-replaced teeth. Because it is only known from a partial jaw from a juvenile, little more than general information can be drawn from it at this point.