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Scolosaurus

Nopcsa, 1928 SKOH-lo-SOR-us

From Greek 'skolos' (stake, thorn, prickle) + 'sauros' (lizard), meaning 'thorn lizard' or 'spiked lizard', referring to the spiky armor projections.

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Scolosaurus is an extinct genus of ankylosaurid dinosaurs within the subfamily Ankylosaurinae. It is known from the lower levels of the Dinosaur Park Formation and upper levels of the Oldman Formation in the Late Cretaceous (latest middle Campanian stage, about 76.5 Ma ago) of Alberta, Canada. The genus contains two species, S. cutleri and S. thronus. The type species, S. cutleri, measured up to 5.6 meters (18 ft) in length and 2.2 metric tons (2.4 short tons) in body mass.

Diagnosis

  1. Osteoderms predominantly conical, subconical, or mammillary in shape, with a virtual absence of the oval to subrectangular, low-keeled osteoderms seen in Dyoplosaurus and Euoplocephalus
  2. Presacral rod of four dorsosacral vertebrae with noticeably constricted intervertebral faces
  3. Ilia weakly divergent; ischium with an unusually straight proximal border and a slight posterior inflection of the shaft distally
  4. Forelimb well armored with conical spines; humerus more robust with a more distally expanded deltopectoral crest, and radius more elongate and sigmoidal, than in Euoplocephalus
  5. First cervical half-ring anteroposteriorly broad, its osteoderms with a posteriorly situated apex and a rugose, perforate surface texture
  6. Oval sacral fenestrae and hoof-shaped pedal unguals, contrasting with the larger fenestrae and more triangular unguals of Dyoplosaurus

Species (2)

Scolosaurus cutleri Nopcsa, 1928

Type species

Named for William Edmund Cutler, the independent fossil collector who discovered the holotype in 1914 and was seriously injured when the specimen fell during excavation.

Holotype
NHMUK PV R 5161 , Natural History Museum
Material
Nearly complete postcranial skeleton with dermal armor in situ; skull, part of the tail, and right-side extremities absent
Horizon
lower Dinosaur Park Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Dead Lodge Canyon, Alberta, Canada

Scolosaurus thronus Penkalski, 2018

From Latin 'thronus' (elevated seat, throne), for the species' high stratigraphic position in the Dinosaur Park Formation and its quarry atop a butte.

Holotype
ROM 1930 , Royal Ontario Museum
Material
Partially articulated skeleton with skull and teeth, dorsal vertebrae, a complete synsacrum, sacral ribs, most caudals, scapula, partial ilia, humerus, a cervical half-ring, osteoderms, and skin.
Horizon
upper Dinosaur Park Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Sternberg Quarry 112, Red Deer River, Alberta, Canada
Diagnosis
  1. Eight vertebrae in the synsacrum (4-2-2, plus cd1), one fewer than in the type species
  2. Proximal caudal neural spines craniocaudally compressed and curved cranially, unlike the erect, tapering spines of more distal caudals
  3. Several osteoderm shapes with no counterparts in the type species, including more pronounced radial ribbing or fluting on some postcervical osteoderms
  4. Proximal caudal osteoderms more strongly keeled
  5. A large (28 cm), high osteoderm that is weakly mammillary, keeled cranially, and ribbed, with an open subconical apex

References

  1. Arbour, V. M.; Currie, P. J. (2013). Euoplocephalus tutus and the diversity of ankylosaurid dinosaurs in the Late Cretaceous of Alberta, Canada, and Montana, USA. PLOS ONE 8(5): e62421. doi:10.1371/journal.pone.0062421

    Gives the holotype locality as Quarry Q080 with a UTM position, the source of the coordinate, noting uncertainty over the quarry.

    arbour2013a
  2. Nopcsa, B. F. (1928). Palaeontological notes on reptiles. Geologica Hungarica, Series Palaeontologica 1(1): 1-84. Institutum Regni Hungariae Geologicum.

    Erects Scolosaurus cutleri as section VI of the monograph.

    nopcsa1928a
  3. Penkalski, P.; Blows, W. T. (2013). Scolosaurus cutleri (Ornithischia: Ankylosauria) from the Upper Cretaceous Dinosaur Park Formation of Alberta, Canada. Canadian Journal of Earth Sciences 50(2): 171-182. Canadian Science Publishing. doi:10.1139/cjes-2012-0098

    Reinstates Scolosaurus as a valid ankylosaurid distinct from Euoplocephalus and Dyoplosaurus, with a revised diagnosis based on osteoderm, cervical half-ring, forelimb, and pelvic characters.

    penkalski2013b
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the hip height estimate, and the appearance features.

    jones2026a
  5. Penkalski, P. (2018). Revised systematics of the armoured dinosaur Euoplocephalus and its allies. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 287(3): 261-306. Schweizerbart. doi:10.1127/njgpa/2018/0717 penkalski2018a