Albalophosaurus
Encyclopedia
Albalophosaurus is a genus
of cerapod
ornithischia
n dinosaur
. It was described in 2009
from remains found in 1997 by Yoshinori Kobayashi from the Kuwajima Formation
of central Japan
, outcropping in Hakusan
in the Ishikawa Prefecture
. The holotype
, SBEI 176, consists of cranial bones from an incomplete, disarticulated skull and left lower jaw thought to belong to a single individual. The type species
is named A. yamaguchiorum. The generic name is derived from Latin
albus, "white", and Greek λόϕος (lophos), "crest", a reference to the snow-covered crest of Mount Hakusan. The specific name honours Ichio Yamaguchi en Mikiko Yamaguchi, who discovered and prepared many fossils from the site.
The exact age of the strata from which the remains of Albalophosaurus have been found is not known because of the lack of marine beds containing index fossil
s, but the Kuwajima Formation is known to have formed during the Early Cretaceous
, most likely after the Berriasian
and before the Barremian
based on the ages of underlying and overlying formations. More recent studies suggest that the age of the Kuwajima Formation is most likely Valanginian
—Hauterivian
, although the exact age is still uncertain.
n in a phylogenetic analysis conducted along with the description of the genus, only one ambiguous synapomorphy
of the clade is present in the holotype, and none of the unambiguous synapomorphies that define Ceratopsia are present. Other characteristics, such as those of the dental morphology
of Albalophosaurus, seem to suggest that the genus shares a relation to Ornithopoda. Thus the authors of the original description of the genus refer it to Cerapoda incertae sedis
, and do not consider it to be a ceratopsian.
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 cerapod
Cerapoda
Neornithischia is a clade of the dinosaur order Ornithischia. They are the sister group of the Thyreophora within the clade Genasauria. Neornithischians are united by having a thicker layer of asymmetrical enamel on the inside of their lower teeth...
ornithischia
Ornithischia
Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...
n 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...
. It was described in 2009
2009 in paleontology
-Anomalocaridids:-Arachnids:-Insects:-Cephalopods:Three new species of extinct Octopoda discovered in 2009. The species - Keuppia hyperbolaris, Keuppia levante, and Styletoctopus annae - lived about 95 million years ago, and bear a strong resemblance to modern octopuses, suggesting that the...
from remains found in 1997 by Yoshinori Kobayashi from the Kuwajima Formation
Kuwajima Formation
The Kuwajima Formation is an Early Cretaceous geologic formation. Dinosaur remains are among the fossils that have been recovered from the formation, including Albalophosaurus yamaguchiorum. The multituberculate mammals Hakusanobaatar matsuoi and Tedoribaatar reini have also been recovered from it....
of central Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, outcropping in Hakusan
Hakusan, Ishikawa
is a city located in Ishikawa, Japan.The city was founded on February 1, 2005 from the merger of the city of Mattō with seven towns and villages from Ishikawa District. As of April 1, 2008 population data, the city has an estimated population of 110,654 and a density of 147 persons per km²...
in the Ishikawa Prefecture
Ishikawa Prefecture
is a prefecture of Japan located in the Chūbu region on Honshū island. The capital is Kanazawa.- History :Ishikawa was formed from the merger of Kaga Province and the smaller Noto Province.- Geography :Ishikawa is on the Sea of Japan coast...
. 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...
, SBEI 176, consists of cranial bones from an incomplete, disarticulated skull and left lower jaw thought to belong to a single individual. 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 named A. yamaguchiorum. The generic name is derived from 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...
albus, "white", and Greek λόϕος (lophos), "crest", a reference to the snow-covered crest of Mount Hakusan. The specific name honours Ichio Yamaguchi en Mikiko Yamaguchi, who discovered and prepared many fossils from the site.
The exact age of the strata from which the remains of Albalophosaurus have been found is not known because of the lack of marine beds containing index fossil
Index fossil
Index fossils are fossils used to define and identify geologic periods . They work on the premise that, although different sediments may look different depending on the conditions under which they were laid down, they may include the remains of the same species of fossil...
s, but the Kuwajima Formation is known to have formed during 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...
, most likely after the Berriasian
Berriasian
In the geological timescale, the Berriasian is an age or stage of the Early or Lower Creteceous. It is the oldest or lowest subdivision in the entire Cretaceous. It spanned between 145.5 ± 4.0 Ma and 140.2 ± 3.0 Ma...
and before the Barremian
Barremian
The Barremian is an age in the geologic timescale between 130.0 ± 1.5 Ma and 125.0 ± 1.0 Ma). It is a subdivision of the Early Cretaceous epoch...
based on the ages of underlying and overlying formations. More recent studies suggest that the age of the Kuwajima Formation is most likely Valanginian
Valanginian
In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 140.2 ± 3.0 Ma and 136.4 ± 2.0 Ma...
—Hauterivian
Hauterivian
The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous epoch or a stage in the Lower Cretaceous series. It spans the time between 136.4 ± 2 Ma and 130 ± 1.5 Ma...
, although the exact age is still uncertain.
Phylogeny
Although Albalophosaurus was classified as a basal ceratopsiaCeratopsia
Ceratopsia or Ceratopia is a group of herbivorous, beaked dinosaurs which thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7...
n in a phylogenetic analysis conducted along with the description of the genus, only one ambiguous synapomorphy
Synapomorphy
In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...
of the clade is present in the holotype, and none of the unambiguous synapomorphies that define Ceratopsia are present. Other characteristics, such as those of the dental morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
of Albalophosaurus, seem to suggest that the genus shares a relation to Ornithopoda. Thus the authors of the original description of the genus refer it to Cerapoda incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
, and do not consider it to be a ceratopsian.