Propanoplosaurus
Encyclopedia
Propanoplosaurus is a genus of herbivorous nodosaurid dinosaur
from the Early Cretaceous
Patuxent Formation
of Maryland
. Its type specimen is a natural cast and partial natural mold of a hatchling
.
From 1994 onwards Ray Stanford uncovered an ichnofauna in Maryland
near the border with Washington D.C.. Along with dinosaur footprints the impressions of a neonate nodosaurid were found.
The type species
Propanoplosaurus marylandicus was named and described by Stanford, David Weishampel and Valerie DeLeon in 2011. The generic name combines the Latin
prefix pro~ with the name of the genus Panoplosaurus
because the new species lived earlier than — but resembled much — this already described nodosaurid. The specific name refers to Maryland.
The holotype
, USNM 540686, was found in the Patuxent Formation, dating from the late Aptian
. It consists of the impressions of the back of the head together with a natural cast of the ribcage, some vertebrae, the right forelimb, the right femur and a right foot. The animal is shown laying on its back. The authors rejected the possibility the specimen represented a pseudofossil
or an embryo
. The specimen is the first nodosaurid skeleton from the eastern seaboard
from which previously only nodosaurid teeth named as Priconodon
were known, and the first neonate dinosaur from that region.
The specimen has a preserved length of thirteen centimetres. The total length of the individual was estimated as between twenty-four and twenty-eight centimetres. Only the skull shows osteoderm
s and the authors suggest this was a common developmental stage of all nodosaurids, together with a long middle section of the snout which is characterised by a unique cross-pattern of the bone plates, probably formed by the triangular osteoderms of the maxilla
e.
Propanoplosaurus was by the describers assigned to the Nodosauridae
.
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 Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
Patuxent Formation
Patuxent Formation
The Patuxent Formation is a Cretaceous geologic formation of the Atlantic coastal plain.-Description:The Patuxent formation was first described by W. B. Clark in 1897. The formation is primarily unconsolidated sand and clay. The sand often contains kaolinized feldspar, making it an arkose. Clay...
of Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...
. Its type specimen is a natural cast and partial natural mold of a hatchling
Hatchling
In oviparous biology, a hatchling is the newborn of animals that develop and emerge from within hard-shell eggs. The offspring of birds are often hatched naked and with their eyes closed. The hatchling relies totally on its parents for feeding and warmth. Hatchlings precede nestlings in the chick's...
.
From 1994 onwards Ray Stanford uncovered an ichnofauna in Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...
near the border with Washington D.C.. Along with dinosaur footprints the impressions of a neonate nodosaurid were found.
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...
Propanoplosaurus marylandicus was named and described by Stanford, David Weishampel and Valerie DeLeon in 2011. The generic name combines the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
prefix pro~ with the name of the genus Panoplosaurus
Panoplosaurus
Panoplosaurus is a genus of nodosaurid dinosaur. It was one of the last known nodosaurids, living during the Late Cretaceous in what is now North America; fossils have been located in Alberta, Canada....
because the new species lived earlier than — but resembled much — this already described nodosaurid. The specific name refers to Maryland.
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...
, USNM 540686, was found in the Patuxent Formation, dating from the late Aptian
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
. It consists of the impressions of the back of the head together with a natural cast of the ribcage, some vertebrae, the right forelimb, the right femur and a right foot. The animal is shown laying on its back. The authors rejected the possibility the specimen represented a pseudofossil
Pseudofossil
Pseudofossils are inorganic objects, markings, or impressions that might be mistaken for fossils. Pseudofossils may be misleading, as some types of mineral deposits can mimic lifeforms by forming what appear to be highly detailed or organized structures. One common example is when manganese oxides...
or an embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
. The specimen is the first nodosaurid skeleton from the eastern seaboard
East Coast of the United States
The East Coast of the United States, also known as the Eastern Seaboard, refers to the easternmost coastal states in the United States, which touch the Atlantic Ocean and stretch up to Canada. The term includes the U.S...
from which previously only nodosaurid teeth named as Priconodon
Priconodon
Priconodon is an extinct genus of dinosaur , known from its large teeth. Its remains have been found in the Aptian-Albian age Lower Cretaceous Arundel Formation of Muirkirk, Prince George's County, Maryland.-History:...
were known, and the first neonate dinosaur from that region.
The specimen has a preserved length of thirteen centimetres. The total length of the individual was estimated as between twenty-four and twenty-eight centimetres. Only the skull shows osteoderm
Osteoderm
Osteoderms are bony deposits forming scales, plates or other structures in the dermal layers of the skin. Osteoderms are found in many groups of extant and extinct reptiles, including lizards, various groups of dinosaurs , crocodilians, phytosaurs, aetosaurs, placodonts, and hupehsuchians...
s and the authors suggest this was a common developmental stage of all nodosaurids, together with a long middle section of the snout which is characterised by a unique cross-pattern of the bone plates, probably formed by the triangular osteoderms of the maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
e.
Propanoplosaurus was by the describers assigned to the Nodosauridae
Nodosauridae
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous Period of what are now North America, Asia, Antarctica and Europe.-Characteristics:...
.