Altirhinus Norman, 1998
Altirhinus Norman, 1998
(Zool. J. Linn. Soc. 122 (1-2), January-February: 296
NcZ) "high snout"
al-ti-RIEN-us (Lat. altus "high" +
Gr. rhin-(rhis) "nose, snout" + -us) (m)
named "in recognition of the highly arched nasal bones of the skull
which give the snout of this animal a distinctively elevated profile";
for a large (7-8 m. (23-26 ft.)) iguanodont from Khuren Dukh, Dornogov (East Gobi Province),
south-central Mongolia, notable for the unusual expanded shape of its snout.
The type skull for Altirhinus (PIN 3386/8) has been displayed, referred to and widely
illustrated as a dinosaur called "Iguanodon orientalis" Rozhdestvensky, 1952.
However, the name "Iguanodon orientalis" was originally proposed based on another
very incomplete specimen (jaw fragments) from Mongolia that appear to belong to
an animal distinct from the new "high-snouted" iguanodont; Norman (1996) considered
Rozhdestvensky's type material inadequate to diagnose "Iguanodon orientalis"
in a scientifically useful way.
Altirhinus is known from a fairly complete skull, parts of another skull and jaw,
and various parts of the skeleton from three adult individuals and two possible juveniles.
Some features in Altirhinus parallel those found in later hadrosaurids,
such as a large diastema between the beak and the grinding cheek teeth,
and extra replacement teeth. The expansion of its nasal cavity may be an adaptation
to a seasonally dry climate to help retain moisture using a turbinal system.
However, Altirhinus evolved such characters independently, perhaps in response
to a dry climate with tough vegetation, and is not considered a direct ancestor to hadrosaurs.
In other ways it is a typical iguanodont, with a manus very similar to Iguanodon's,
including a "spike" thumb and a prehensile fifth digit.
Type species: Altirhinus kurzanovi [koor-zuh-NOH-vie] "for the collector of this
new species, Dr. Sergei M. Kurzanov of the Paleontology Institute of the Russian Academy
of Sciences, Moscow, who is renowned for his collecting prowess,
and his work on a wide variety of Mongolian fossil vertebrates."
Ornithopoda Iguanodontidae E. Cret. (Late Aptian/Albian) Mongolia
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