Gargoyleosaurus (meaning "gargoyle lizard") is one of the earliest ankylosaurs known from reasonably complete fossil remains. The holotype was discovered in 1995 at the Bone Cabin Quarry West locality, in Albany County, Wyoming in exposures of the Upper Jurassic (Kimmeridgian to Tithonian faunal stage) Morrison Formation.
The type species, G. parkpinorum (originally G. parkpini) was described by Ken Carpenter et al. in 1998. A mounted skeletal reconstruction of Gargoyleosaurus parkpinorum can be seen at the Denver Museum of Nature and Science and, alongside a couple skeletons of baby Stegosaurus, has been on display there since around 2002. Gargoyleosaurus was present in stratigraphic zone 2 of the Morrison Formation.[Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327–329.]
Discovery
The holotype specimen of
Gargoyleosaurus parkpinorum was collected by Western Paleontology Labs in 1995 and is currently held in the collections of the Denver Museum of Nature and Science,
Denver,
Colorado. Besides the holotype, two other partial skeletons are known (although not yet described). The holotype consists of most of the skull and a partial postcranial skeleton. The specimen was originally described as
Gargoyleosaurus parkpini by Carpenter, Miles and Cloward in 1998, then renamed
G. parkpinorum by Carpenter
et al. in 2001, in accordance with ICZN art. 31.1.2A.
Description
Gargoyleosaurus was a relatively small ankylosaur, reaching in length and in body mass.
Much of the
skull and
skeleton has been recovered, and the
taxon displays cranial sculpturing, including pronounced deltoid
quadratojugal and
squamosal bosses. The taxon is further characterized by a narrow rostrum (in dorsal view), the presence of seven conical teeth in each
premaxilla, an incomplete
osseous nasal septum, a linearly arranged nasal cavity, the absence of an osseus
secondary palate, and, as regards osteoderms, two sets of co-ossified cervical plates and a number of elongate conical spines.
A very unusual feature is the sagittal (midline) osteoderm on the first set of cervical plates; in most other ankylosaurs, these osteoderms are bilateral, i.e. paired with one on each side of the midline.
[ Kilbourne, B. and Carpenter, K. 2005. "Redescription of Gargoyleosaurus parkpinorum, a polacanthid ankylosaur from the Upper Jurassic of Albany County, Wyoming". N. Jb. Geol. Palaont. Abh. 237: 111–160]
Classification
Vickaryous
et al. (2004) place
Gargoyleosaurus parkpinorum within the family
Ankylosauridae of the
Ankylosauria and are in agreement with most previous
phylogenetic hypotheses, which place the
genus as the
sister group to all other ankylosaurids (i.e., members of the Ankylosauridae). These studies however, only utilized the skull, whereas many of the distinctive features of the family Polacanthidae are in the postcranial skeleton. In contrast, a phylogenetic analysis by Soto-Acuña and colleagues in 2021 recovered
Gargoyleosaurus as a nodosaurid.
Below is a reproduced phylogenetic analysis from Soto-Acuña et al. (2021):
See also
-
Timeline of ankylosaur research
-
Carpenter, K., Miles, C. and Cloward, K. (1998). "Skull of a Jurassic ankylosaur (Dinosauria)." Nature 393: 782–783.
-
Carpenter, K. (ed.) The Armored Dinosaurs. pp. 454–483. Indiana University Press, Bloomington.
-
Vickaryous, Maryanska, and Weishampel (2004). "Ankylosauria". in The Dinosauria (2nd edition), Weishampel, D. B., Dodson, P., and Osmólska, H., editors. University of California Press.
-
Killbourne, B. and Carpenter, K. (2005). "Redescription of Gargoyleosaurus parkpinorum, a polacanthid ankylosaur from the Upper Jurassic of Albany County, Wyoming". Neues Jahrbuch für Geologie und Paläontologie, 237, 111–160.
External links
