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I finally got the stupid thing done. Again, criticize or make
suggestions on ANYTHING that you don't like. If you only have a little
bit to say, you might want to send it just to me.
The part where I talk about contemporaneous dinosaur genera and species
is probably a bit outdated, since 1) my primary source was DINOSAURIA,
and 2) I only asked previously for clarification on tyrannosaurs and
ceratop(s)ians. If you are willing to wade through it all,
its much appreciated (The Judith River is a fantastically rich dinosaur
locality, so most "paleoecology" sections wont be this long). I am
unaware of any post-1990 Two-Medicine/Judith River/Horsesheoe Canyon
genera except Achelosaurus and Einisaurus, so please fill me in if you
know any more.
I repetitively alternate between "included" (which sounds like I'm
not listing them all) and
"consisted of" (which implies there weren't any others) when talking
about dinosaur groups. Any suggestions on how to phrase these better would be
Especially uncertain points are marked with an asterisk and a number. The
specific queries are grouped together before the bibliography. Thanks in
advance for any comments, and thanks again to all who answered my original
GENUS _Euoplocephalus_ (Lambe, 1910)
Synonyms: _Stereocephalus_ (Lambe, 1902)
_Palaeoscincus_ (Lambe, 1902)
_Anodontosaurus_ (Sternberg, 1929)
_Dyoplosaurus_ (Parks, 1924)
_Scolosaurus_ (Nopsca, 1928b)
_Euoplocephalus_ _tutus_ (Lambe, 1910)
Etymology:(Greek) Eu ("well", "good") + oplos ("armoured") + kephale ("head")
(*1) tutus ("safe, secure)
Synonyms: _Stereocephalus_ _tutus_ (Lambe, 1902)
_Palaeoscincus_ _asper_ (Lambe, 1902)
_Dyoplosaurus_ _acutosquamaeus_ (Parks, 1924)
_Scolosaurus_ _cutleri_ (Nopsca, 1928a)
_Anodontosaurus_ _lambei_ (Sternberg, 1929)
Holotype: NMC 210
Referred specimens: AMNH 5211, AMNH 5216, AMNH 5223, AMNH 5245, AMNH
5266, AMNH 5337, AMNH 5403, AMNH 5404, AMNH 5405, AMNH 5406, AMNH 5409,
AMNH 5440, AMNH 5470, BMNH R4947, BMNH R5161 (holotype: _S_._cutleri_),
NMC 349, NMC 1349 (holotype, _P_._asper_), NMC 2252, NMC 2253, NMC
8530 (holotype, _A_._lambei_), NMC 8876, ROM 784 (holotype:
_D_._acutosquamaeus_), ROM 788, ROM 813, ROM 832, ROM 833, ROM 1930, ROM
7761, ROM 7763, ROM 7764, ROM 7765, ROM 7766, ROM 7767, ROM 7770, UA 31,
USNM 7943, USNM 8360, USNM 11892, USNM 16747
Formation & lovation: Judith River Group
Montana, United States
Two Medicine Formation
Montana, United States
Horseshoe Canyon Formation
Age: late Campanian-early Maastrichtian
THYREOPHORA (Nopsca, 1915)
EURYPODA (Sereno, 1986)
ANKYLOSAURIA (Osborn, 1923)
ANKYLOSAURIDAE (Brown, 1908)
Estimated (adult) length: 6-7 meters
Estimated (adult) body weight: ~2 tonnes
_Euoplocephalus_ _tutus_ was the most common ankylosaur in western
North America during its time. Its armour consisted of plates, scutes,
ossicles and keels arranged in transverse bands across the body. The
scutes were heavily vascularized, and may have served a thermoregulatory
function. The head was very well armoured, even down to having armour plates
on the eyelids. The fair degree of lateral flexibility in the anterior
caudals, combined with the fused caudals and ossified tendons of the distal
part of the tail, made the club a formidible weapon. The nasal
passages were fairly complex, and may have given _E_._tutus_ a good sense of
smell. However, it has also been suggested that they served to warm
and moisten inhaled air as in modern endotherms.
The late Campanian Two Medicine Formation was formed on the upper
part of a coastal plain, near the young Rocky Mountains. The climate
here was semi-arid, with small streams and seasonal lakes (*2). Vegetation
consisted of berry bushes, dogwoods (*3), evergreens, and cycads.
Ornithopods from this area consisted of the hypsilophodont
_Orodromeus_ _makelai_ and lambeosaurine and hadrosaurine
hadrosaurs, including _Maiasaura_ _peeblesorum_.
Ceratopsians included _Achelousaurus_ _horneri_, _Brachyceratops_
_montanenesis_, _Chasmosaurus_, _Einiosaurus_ _procurvicornis_,
_Styracosaurus_ _ovatus_, and possibly _Centrosaurus_ and _Leptoceratops_
The nodosaurid _Edmontonia_ _rugosidens_ is known from this
formation, in addition to the ankylosaurid _Euoplocephalus_ _tutus_.
The small theropods _Troodon_ _formosus_, _Dromaeosaurus_, and
_Saurornitholestes_ (*6) were present, as were the larger forms
_Albertosaurus_ and _Aublysodon_ _mirandus_.
The Judith River Group was formed on the lower part of the same
coastal plain as the Two Medicine Formation, lying adjacent to the
Western Interior Seaway. The climate was wetter, with swamps,
freshwater ponds, and meandering rivers flowing into the sea. The vegetation
here was more abundant and included ferns, palms, and cycads growing in the
shadows of cypress, pine, sequoia, magnolia, dogwood, and poplar trees.
Dinosaurs were more common and diverse here (*7). Ornithopods
included of the the hypsilophodont _Thescelosaurus_ _negelctus_, the
hadrosaurines _Brachylophosaurus_ _canadensis_, _B_._goodwini_,
_Prosaurolophus_ _maximus_, _Gryposaurus_ _notabilis_, "Kritosaurus"
incurvimanus, and possibly _Maiasaura (*9). Lambeosaurines included
_Corythosaurus_ _casuarius_, _Lambeosaurus_ _lambei_, _L_. _magnicristatus_,
and _Parasaurolophus_ _walkeri_. (Indeterminate hadrosaur remains include
_Cionodon_ _stenopsis_, _Dysganus_ _encaustus_, _Diclonius_ _pentagonus_,
_D_. _calamarius_, _Hadrosaurus_ _breviceps_, _H_. _paucidens_, _Pteropelyx_
_grallipes_, _Trachodon_ _altidens_, _T_. _marginatus_, _T_._mirabilis_,
and _T_. _selwyni_).
Pachycephalosaur remains include _Stegoceras_ _validum_,
_Gravitholus_ _albertae_, _Ornatotholus_ _browni_, and
Ceratopsians included _Avaceratops_ _lammersi_, _Anchiceratops_
_ornatus_, _Chasmosaurus_ _belli_, _C_. _russelli_, _Monoclonius_ _crassus_,
_Centrosaurus_ _apertus_, and _Styracosaurus_ _albertensis_.
(Indeterminate ceratopsian remains include _Ceratops_ _montanus_,
_Monoclonius_ _recurvicornis_, _M_. _sphenocerus_, _M_. _fissus_,
_Dysganus_ _peiganus_, _D_._bicarinatus_, _D_. _encaustus_, and _D_.
Ankylosaurs consisted of the nodosaurids _Edmontonia_ _rugosidens_,
_E_._longiceps_, and _Panoplosaurus_, as well as the
ankylosaurid _Euoplocephalus_ _tutus_ (Indeteriminate ankylosaur remains
include _Palaeoscincus_ _costatus_).
Theropod included the poorly known _Richardoestesi_
_gilmorei_ and the troodont _Troodon_ _formosus_ (Indeterminate
troodont remains include _Paronychodon_ _lacustris_ and _Zapsalis_
_abradens_) The dromaeosaurs _Dromaeosaurus_ _albertensis_ and
_Saurornitholestes_ _langstoni_, the elmisaurids _Chrirostenotes_ and
_Elmisaurus_ _elegans_, the caenagnathids _Caenagnathus_ _collinsi and
_C_._sternbergi_, and the ornithomimids _Struthiomimus_ _altus_,
_Dromicieomimus_ _samueli_, and _Ornithomimus_ were also present
(Indeterminate ornithomimid remains include _Ornithomimus_ _tenuis_).
Large theropods consisted of _Albertosaurus sarcophagus_,
_Gorgosaurus_ _libratus_, _Daspleteosaurus_ _torosus_, and _Aublysodon_
_mirandis_ (Indeterminate theropods include _Laelaps_ _explanatus_,
_L_. _laevifrons_, and _Aublysodon_ _lateralis_).
Also known from the Judith River Formation is a segnosaur possibly
referrable to _Erlikosaurus_ (*10).
The early Maastrichtian Horseshoe Canyon Formation was
laid down on the same lower coastal plain of the Judith
River Formation (*11).
Ornithopods included the hypsilophodont _Parksosaurus_ _warreni_ and
the hadrosaurines _Edmontosaurus_ _regalis_, _Saurolophus_ _osborni_,
and _Hypacrosaurus_ _altispinus.
Pachycephalosaurs included _Stegoceras_ _edmontonense_.
Ceratopsian included _Anchiceratops_ _ornatus_, _Arrhinoceratops_
_brachyops_, and _Pachyrhinosaurus_ _canadensis_.
Ankylosaurs consisted of the nodosaurid _Edmontonia_ _longiceps_, as
well as the ankylosaurid _Euoplocephalus_ _tutus_.
The ornithomimids _Ornithomimus_ _edmontonensis_, _Struthiomimus_
_altus_, _Dromicieomimus_ _brevitertius_, the elmisaurid _Chirostenotes
pergracilis_, the troodont _Troodon_ _formosus_, and the dromaeosaurs
_Dromaeosaurus_ and _Saurornitholestes_ (*13) were also present. Large
theropods inlcuded _Albertosaurus_ _sarcophagus_ and _Daspletosaurus_(*14).
*1: Is this greek as well?
*2: Is "seasonal" the right word here? Meaning they dry up each year.
*3: Are both of these angiosperms?
*5: Anyone know anything about these presence of these two?
*6: Does this belong under Troodon?
*7: For real or a bias of the fossil record?
*9 Anyone know anything about this?
*10: How about this? Any other segnosaur remains?
*11: A little more info on the environment here would be nice. I assume
the coastal plain was now larger because the sea was shrinking?
*13: Dinosauria lists "cf. Dromaeosaurus sp.", so how concrete are the
remains? Again, is Saurornitholestes valid?
*14: Anyone know anything about Horseshoe Canyon Daspletesaus remains?
Finally: which ceratopsians are thought to represent ontogenetic
growth stages of a single genus? What other sorts of critters besides
dinosaurs were important in the Two Medicine, Judith River, and Horseshoe
Brown, B. 1908. The Ankylosauridae, a new family of armored dinosaurs
from the Upper Cretaceous. Bull. Am. Mus. Nat. Hist. 24: 187-201
Carpenter, K. 1982. Skeletal and dermal armor reconstruction of
_Euoplocephalus_ _tutus_ (Ornithischia: Ankylosauridae) from the Late
Cretaceous Oldman Formation of Alberta. Can. J. Earth Sci. 19: 689-697
Coombs, W.P., Jr. 1971. The Ankylosauria. Ph.D. dissertation, Columbia
Univ., New York.
---- 1972. The bony eyelid of _Euoplocephalus_ (Reptilia, Ornithischia).
J. Paleontol. 46: 637-650
---- 1978a. The families of the ornithischian dinosaur order Ankylosauria.
Palaeontology. 21: 143-170
---- 1978b. Forelmb muscles of the Ankylosauria (Reptilia, Ornithischia).
J. Paleontol. 52: pp. 642-658
---- 1978c. Theoretical aspects of the cursorial adaptations in
dinosaurs. Q. Rev. Biol. 53: 393-418
---- 1978d. An endocranial cast of _Euoplocephalus_ (Reptilia,
Ornithischia). Palaeontographica A 161: 176-182.
---- 1979. Osteology and myology of the hindlimb in the Ankylosauria
(Reptilia, Ornithischia). J. Paleontol. 53: 666-684
---- 1986. A juvenile ankylosaur referrable to the genus _Euoplocephalus_
(Reptilia, Ornithischia). J. Vert. Palaeontol. 6: 162-173
Lambe, L.M. 1902. New genera and species from the Belly River Series
(mid-Cretaceous). Contrib. Canadian Palaeontol. Geol. Surv. Can. 3: 25-81
---- 1910. Note on the parietal crest _Centrosaurus_ _apertus_, and a
proposed new generic name for _Stereocephalus_ _tutus_. Ottawa Nat. 14:
Nopsca, F. 1928a. Paleontological notes on reptiles. Geol. Hungarica,
Ser. Paleontol. 1: 1-84
---- 1928b. The genera of reptiles. Paleobiologica, 1: 163-188
Olshevsky, G. 1979. The ankylosaur family tree. George Olshevsky, San
Diego, CA. (Private printing)
Parks, W.A. 1924. _Dyoplosaurus_ _acutosquameus_, a new genus and species
of armoured dinosaur; with notes on a skeleton of _Prosaurolophus_
_maximus_. Univ. Toronto Stud. (Geol. Ser.) 18: 1-35
Sereno, P.C. 1986. Phylogeny of the bird-hipped dinosaurs (Order
Ornithischia). Natl. Geogr. Soc. Res 2: 234-256
Sternberg, C.M. 1929. A toothless armoured dinosaur from the Upper
Cretaceous of Alberta. Bull. Natl. Mus. Can. 54: 28-33