Cretaceous "Hell Creek Faunal Facies"; Late Maastrichtian

Phillip Bigelow

1. Insects
2. Aquatic Invertebrates
3. Mammalia
4. Lower Vertebrates
5. Dinosauria
6. Freshwater Algae
7. Palynomorphs (fossil pollen)
8. Megaflora

Insect Evidence From The Hell Creek Formation

(excerpt from Johnson et al. (2000)]

"Previous studies have indicated no evidence for mass extinction among insects at the K-T boundary. These studies were based on global, family-level compilations of body-fossil data that indicated no deviation from background rates of extinction. In contrast, the palynologic and megafloral evidence cited above demonstrates a major extinction of plant taxa at the K-T boundary. To test these opposite conclusions, we examined insect-mediated plant damage on 6,000 leaves in a succession of 78 of our megafloral localities in southwestern North Dakota from a section that spans a 2.0 m.y. interval of the late Maastrichtian Hell Creek Formation and earliest Puercan Ludlow Member of the Fort Union Formation. All characterizable leaf hosts from these floras were assigned to morphotypes and/or Linnean taxa, providing explicit recognition of plant hosts. We identified 42 types of insect damage, representing insect herbivory from four functional feeding groups: external foliage feeders, leaf miners, gallers, and piercer-and-suckers. For the Hell Creek megaflora, 41 types of damage were identified, including several conspicuous examples of galls and scales on primary veins, serpentine mines, and diagnostic slot-hole feeding, each occurring monospecifically and abundantly on separate species of Lauraceae, Platanacae, and Cannabacae. For the [overlying, Tertiary-age] Fort Union megaflora, only 17 types of damage were identified; abundance levels were found to be significantly lower; and the associations were more generalized, lacking host-specific associations. These data demonstrate that, at local scales, insect herbivory suffered dramatically during the terminal Cretaceous event, with no evidence of subsequent recovery. Levels of herbivore diversity remained depressed until pronounced vegetational shifts in the Western Interior of North America during the Early Cenozoic Thermal Maximum in the latest Paleocene to early Eocene time."

Reference:

Johnson K. R., D. Nichols, C. Labandeira, and D. Pearson. 2000. Devastation of terrestrial ecosystems at the K-T boundary in North America: The first calibrated record of plant and animal response to the Chicxulub impact. In Catastrophic Events and Mass Extinctions: Impacts and Beyond, Vienna, pp. 85-86, LPI Contribution No. 1053, Lunar and Planetary Institute, Houston.

Aquatic Invertebrates from the Hell Creek Formation

LINNAEAN NAME	COMMENTS
Plesielliptio postbiplicatus (Whitfield)	Fresh water Pelecypod (fwp)
Plesielliptio gibbosoides (Whitfield)	fwp
Plesielliptio whitfieldi Russell 1976	fwp
Rhabdotophorus aldrichi (White)	fwp
Pleurobema cryptorhynchus (White)	fwp
Plethobasus aesopiformis (Whitfield)	fwp
Plethobasus biesopoides (Whitfield)	fwp
Quadrula cylindricoides (Whitfield)	fwp
Proparreysia verrucosiformis (Whitfield)	fwp
Proparreysia holmesiana (White)	fwp
Proparreysia barnumi (Pilsbry)	fwp
Proparreysia percorrugata (Whitfield)	fwp
Proparreysia pyramidatoides (Whitfield)	fwp
Proparreysia letsoni (Whitfield)	fwp
Proparreysia retusoides (Whitfield)	fwp
Proparreysia corbiculoides (Whitfield)	fwp
Proparreysia paucinodosa Russell 1976	fwp
Obovaria? pyramidella (Whitfield)	fwp
Corbicula cf. subelliptica (Meek and Hayden)	fwp
Sphaerium beckmani Russell 1976	fwp. "Pill clam". "Nut clam". "Fingernail clam". "Pea clam". Family Sphaeriidae.
Pleiodon gen. (sub. gen. Pleiodon) Conrad 1834	fwp
Campeloma sp.	Fresh water snail. See Cooley (2001), below. (Genus is misspelled in the abstract)
Anomia gryphorhyncha Meek. HYPOTYPE. YPM 24103; other specimen YPM-45828	Bivalve. Family Anomiidae. From a marine facies ("tongue") in South Dakota.
Corbicula sp. A. YPM 45892	From a marine facies ("tongue") in South Dakota. Modern members of this genus live in fresh water
Crassostrea subtrigonalis (Evans & Shumard). YPM 45875.	Oyster. Family Ostreidae. Collected from a marine facies ("tongue") in South Dakota.
Granocardium (Ethmocardium) whitei (Dall). YPM 46205.	Bivalve. Family Cardiidae. Collected from a marine facies ("tongue") in South Dakota.
Hiatella? sp. A. HYPOTYPE. YPM 24688.	Bivalve. Present members of this genus are rock borers. Collected from a marine facies ("tongue") in South Dakota.
Leptosolen sp. indet. HYPOTYPE. YPM 24746.	Bivalve. Family Cultellidae. Collected from a marine facies ("tongue") in South Dakota.
Sphenodiscus lenticularis (Owen). YPM 44661	Ammonite. From a marine facies ("tongue") in South Dakota.
Discoscaphites rossi Landman & Waage. YPM 27082.	Microconch of an ammonite. From a marine facies ("tongue") in South Dakota.
undet. Scaphitidae. YPM 32430	Ammonite. From a marine facies ("tongue") in South Dakota. Other attributes: specimen has hooks on it's shell.

Comments:
All "Bug Creek Faunal Facies" taxa are excluded, due to an almost certain mixing of Cretaceous and Paleocene taxa.

Russel (1976:366) claims that "Gastropods, some of which were identified but not described by Whitfield, are represented in the collection by enough material to show that a large and varied assemblage is present in the Hell Creek beds." If I can find a published source, I will add these fresh water gastropods to this list.

Regarding the survival of these pelecypods into the Paleocene, Russel (p. 367) stated: "...none has been shown as yet to occur in Paleocene strata".

Regarding the uniqueness of the Hell Creek Formation pelecypods, Russel (p. 367) wrote: "The largest number of Hell Creek species occurring in other faunas is in the Lance Formation, although the number is only five or six." (see also Morris, 1990).

Does this indicate freshwater molluscan provincialism in the North American interior during the latest Cretaceous?

All of the MARINE INVERTEBRATES were collected in South Dakota (Ziebach County) from the lower part of the Hell Creek Formation in 1961-1962 by K.M. Waage. These specimens were collected from the Breien Member of the formation. "YPM" is the acronym for a Yale-Peabody Museum specimen number.

References:

1. Cooley, J. B. 2001. Taphonomy and sedimentology of a tyrannosaurid locality from the late Cretaceous (Maastrichtian) Hell Creek Formation of eastern Montana. [Abstract]. Session no. 82. Geological Society of America Abstracts with Programs. Geological Society of America Annual Meeting , November 5-8, 2001, Boston, Massachusetts.
2. Morris, P.J. 1990. Diversity and extinction: Detailed examination of freshwater molluscan faunas in an African Rift lake and at the K-T boundary. Geological Society of America Abstracts with Programs 22(7): A356.
3. Morris, P.J., and P.G. Williamson, 1988. Pleiodon (Conrad) (Bivalvia: Mutelidae: Pleiodoninae) from the late Cretaceous of Montana: A First North American Record for the Mutelidae. Journal of Paleontology, v.62, no. 5, pp.758-765.
4. Russell, L. S. 1976. Pelecypods of the Hell Creek Formation (Uppermost Cretaceous) of Garfield County, Montana. Canadian Journal of Earth Science, vol. 13, pp. 365-388.
5. Whitfield, R. P. 1903. Notice of six new species of Unios from the Laramie group. Bulletin of the American Museum of Natural History, vol. 19(15), pp. 483-487.
6. Whitfield, R. P. 1907. Remarks on and descriptions of new fossil Unionidae from the Laramie clays of Montana. Bulletin of the American Museum of Natural History, vol. 23(26), pp. 623-628.

Mammalia from the Hell Creek Formation

LINNAEAN NAME	COMMENTS
Mesodma hensleighi Lillegraven 1969	A multituberculate
Mesodma formosa (Marsh, 1889)	A multituberculate
Mesodma thompsoni Clemens 1964	A multituberculate
?Neoplagiaulax burgessi Archibald 1982	A multituberculate
?Neoplagiaulacidae gen. et sp. indet	A multituberculate
Cimolodon nitidus Marsh 1889	A multituberculate
Cimolomys gracilis	A multituberculate
Meniscoessus robustus Marsh 1989	A multituberculate
Essonodon browni Simpson 1927	A multituberculate
Cimexomys minor Sloan and Van Valen 1965	A multituberculate
Paracimexomys priscus Archibald 1982	A multituberculate
Ectonodon montanensis Simpson 1927	TYPE.-Amer. Mus. No. FM14406, an isolated left upper molar from Crooked Creek. A metatherian. The genus was reassigned as a junior synonym of Didelphodon (by McKenna & Bell, 1997). The current status of the species is not clear. In the mid-1990s, the museum reported the specimen lost.
Alphadon marshi Simpson 1927	A metatherian
Alphadon wilsoni Lillegraven 1969	A metatherian
Alphadon lulli Clemens 1966	A metatherian
Alphadon rhaister Clemens 1966	A metatherian
Glasbius twitchelli Archibald 1982	A metatherian
Pediomys elegans Marsh 1889	A metatherian
Pediomys cooki Clemens 1966	A metatherian
Pediomys krejcii Clemens 1966	A metatherian
Pediomys hatcheri (Osborn 1898)	A metatherian
Pediomys florencae Clemens 1966	A metatherian
?Pediomys cf. P. florencae Clemens 1966	A metatherian
Didelphodon vorax Marsh 1889	A BADGER-SIZE metatherian! One of the larger Mesozoic mammals
Gypsonictops hypoconus	A eutherian
Gypsonictops illuminatus	A eutherian
Cimolestes incisus Marsh 1889	A eutherian
Cimolestes cerberoides Lillegraven 1969	A eutherian
Cimolestes propalaeoryctes Lillegraven 1969	A eutherian
Cimolestes stirtoni Clemens 1973	A eutherian
Cimolestes magnus Clemens and Russell 1965	A eutherian
Batodon tenuis Marsh 1892	A eutherian
Purgatorius ceratops Van Valen and Sloan 1965	A eutherian. Primatomorph.

Comments:

Although Archibald (1982) listed many marsupials in the Hell Creek Formation, a new character trait analysis by Rougier et. al (1998) shows that all of Archibald's "marsupials" are in fact members of a more inclusive clade called Metatheria. Amazingly, this new study also indicates that no true marsupials have yet been found from the Mesozoic.

All "Bug Creek Faunal Facies" taxa excluded, due to an almost certain mixing of Cretaceous and Paleocene taxa.

References:

1. Archibald, J. D. 1982. A study of Mammalia and Geology across the Cretaceous-Tertiary Boundary in Garfield County, Montana. University of California Publications in Geological Sciences, volume 122, pages 242-243.
2. Lillegraven, J. A., Z. Kielan-Jaworowska, and W. A. Clemens (eds.). 1979. Mesozoic Mammals: The First Two-Thirds of Mammalian History. University of California Press. 311 pages.
3. Rougier, G.W., J.R. Wible, and M.J. Novacek. 1998. Implications of Deltatheridium specimens for early marsupial history. Nature, volume 396, pages 459-463.
4. Simpson GG. 1927. Multis, metatherians and Gypsonictops, Mammalian fauna of the Hell Creek Formation of Montana. American Museum Novitates 267:1-7.
5. Van Valen, L., and R. E. Sloan. 1965. The earliest primates. Science, volume 150, pages 743-745.

Lower Vertebrates from the Hell Creek Formation

LINNAEAN NAME	VERNACULAR NAME and COMMENTS
Lissodus selachos (Estes) 1964	Hybodontid shark
Squatirhina americana Estes 1964	Orectolobid shark
Brachaelurus estesi (Herman) 1975	Orectolobid shark (rare)
Ischyrhiza avonicola Estes 1964	sawfish (extremely rare)
Myledaphus bipartitus Cope 1876	ray (relatively common)
"Acipenser" eruciferus (Cope) 1876	sturgeon
"Acipenser" albertensis Lambe 1902	sturgeon
Protoscaphirhynchus squamosus Wilmovsky 1956	sturgeon
Paleopsephurus wilsoni MacAlpin 1947	Paddlefish (Polydontid, see Grande and Bemis, 1991)
Large, undescribed Polyodontidae	Paddlefish (Polydontid, see Grande and Bemis, 1991)
Melvius thomasi Bryant 1987	a large amiid fish (family that includes the modern Bowfin)
Kindleia fragosa Jordan 1927	small amiid fish (ubiquitous). Closely related to the modern Bowfin
Lepisosteus occidentalis (Leidy) 1856	garfish ("gar pike") (extremely common)
Belonostomus longirostris (Lambe) 1902	A long-snouted slender fish (affinity= ?Aspidorhynchidae). Rare
Belonostomus sp.	see above
Phyllodus paulkatoi Estes and Hiatt 1978	fish with columnar teeth
Palaeolabrus montanensis Estes 1969	fish (incertae sedis)
Platacodon nanus Marsh 1889	small teleost fish
Pachyrhizodontoidei indet.	fish
Albanerpeton nexuosus Estes 1981	salamander
Opisthotriton kayi Auffenberg 1961	salamander
Prodesmodon copei Estes 1964	salamander (extremely rare)
Scapherpeton tectum Cope 1876	salamander (most common salamander.)
Lisserpeton bairdi Estes 1965	salamander
cf. Piceoerpeton sp.	salamander
Habrosaurus dilatus Gilmore 1928	LARGE salamander (160 cm long)
Scotiophryne pustulosa Estes 1969	small frog
Plesiobaena antiqua Lambe 1902	Baenid turtle
Eubaena cephalica (Hay) 1904	Baenid turtle
Stygiochelys estesi Gaffney and Hiatt 1971	Baenid turtle
Palatobaena bairdi Gaffney 1972	Baenid turtle
Neurankylus eximius Lambe 1902	Largest baenid turtle in Hell Cr. Formation
Thescelus insiliens Hay 1908	Baenid turtle
Emarginochelys cretacea Whetstone 1978	Chelydrid-like turtle
Chelydridae indet.	Chelydrid-like turtle
"Clemmys" backmani Russell 1934	Thin-shelled macrobaenid turtle
Adocus sp.	Flattened dermatemydid turtle
Basilemys sinuosa Riggs 1906	BIG dermatemydid land tortoise! 1+ meters long
Dermatemydine indet.	Dermatemydid turtle
Kinosternidae?	Small kinosternid turtle
Trionyx (Trionyx)	Similar in appearance to living trionychid turtle
Trionyx (Aspideretes)	Large trionychid turtle
"Plastomenus" A	Trionychid turtle
"Plastomenus" C	Trionychid turtle
Helopanoplia distincta Hay 1908	Trionychid turtle
Aspideretoides foveatus Gardiner et al. 1995	Trionychid turtle
Compsemys victa Leidy 1856	Baenid? turtle
Champsosaurus sp. indet.	Long-snouted aquatic diapsid (Suborder Choristodera)
Haptosphenus placodon Estes 1964	Teiid lizard
Leptochamops denticulatus (Gilmore) 1928	Small teiid lizard
Peneteius aquilonius Estes 1969	Teiid lizard
Chamops segnis Marsh 1892	Largest teiid lizard in Hell Creek Formation
Contogenys sloani Estes 1969	?Scincid? lizard
Exostinus lancensis Cope 1873	Xenosaurid lizard
Odaxosaurus piger Gilmore 1928	Anguid lizard
Proxestops jepseni (Gilmore) 1942	Anguid lizard
Parasaniwa wyomingensis Gilmore 1928	Necrosaurid lizard
Paraderma bogerti Estes 1964	?Helodermatid? lizard
Palaeosaniwa canadensis Gilmore 1928	A LARGE Monstersauria lizard (Balsai, 2001), closely related today's varanid lizards. It was the largest lizard in the Hell Cr. Fm, and Balsai has even suggested that it may have been venomous. We're talking MONITOR lizard-size!
Boidae indet.	Snake. Earliest-known boid. See Bryant (1989:49, 76)
Borealosuchus sternbergi (Gilmore 1910); = "Leidyosuchus" sternbergi Gilmore	Crocodyloid; See Brochu (1997)
Brachychampsa montana Gilmore 1911	Alligatoroid; possibly a turtle-eater (see Carpenter and Lindsey, 1980 ref., below).
"Undescribed alligatorine A"	Alligatoroid
"Undescribed alligatorine B"	Alligatoroid
Thoracosaurus neocesariensis(DeKay) 1842	Marine crocodyloid. Extant marine crocs are sometimes found in rivers. This occurrence is reported within the terrestrial Hell Creek Formation by Estes and Berberian (1970). See ref. below.
Pterosauria gen. et sp. indet.	These records of pterosaur remains from the Hell Creek Formation are two indeterminate specimens, which have been recorded from North Dakota but not described (Johnson et al., 2000; Pearson et al., 2002). See Johnson et al. and Pearson et al. references, below
Pterosauria (azhdarchid)	Another pterosaur. See Henderson and Peterson (2006) reference, below

Comments:
The following may be Paleocene in age. Stratigraphic position highly dubious. Included for historical context. It is best to exclude the taxon from the "Hell Creek Faunal Facies":
**Coriops amnicolus Estes 1969, fish. May be Paleocene in age.
**Proamphiuma cretacea Estes 1969, eel-like salamander. May be Paleocene in age.
**Colpodontosaurus crascens Estes 1964, Necrosaurid lizard. May be Paleocene in age.

All "Bug Creek Faunal Facies" taxa excluded, due to almost certain mixing of Cretaceous and Paleocene taxa.

References:

1. Balsai, M. J. 2001. The phylogenetic position of Palaeosaniwa and the early evolution of the Platynotan (Varanoid) anguimorphs. Unpublished PhD dissertation. University of Pennsylvania.
2. Brochu, C. 1997. A review of "Leidyosuchus" from the Cretaceous through Eocene of North America. Journal of Vertebrate Paleontology 17[4]:679-697.
3. Bryant, L.J. 1989. Non-dinosaurian lower vertebrates across the Cretaceous-Tertiary Boundary in Northeastern Montana. University of California Publications in Geological Sciences volume 134. University of California Press, 107 pages.
4. Carpenter, K., and D. Lindsey. 1980. The dentiary of Brachychampsa montana Gilmore (Alligatorinae; Crocodylidae), a late Cretaceous turtle-eating alligator. Journal of Paleontology, vol. 54(6):1213-1217.
5. Estes, R., and P. Berberian. 1970. Paleoecology of a late Cretaceous vertebrate community from Montana. Breviora volume 343, 35 pages.
6. Gardner, James D., Anthony P. Russell, and Donald B. Brinkman. 1995. Systematics and taxonomy of the soft-shelled turtles (Family Trionychidae) from the Judith River Group (mid-Campanian) of North America. Canadian Journal of Earth Sciences 32: 631-643.
7. Grande, L. and W. E. Bemis. 1991. Osteology and phylogenetic relationships of fossil and Recent paddlefishes (Polydontidae) with comments on the interrelationships of Acipenseriformes. Journal of Vertebrate Paleontology, vol. 11, supplement to number 1, 121 pages.
8. Henderson, M. D. & J. E. Peterson. 2006. An azhdarchid pterosaur cervical vertebra from the Hell Creek Formation (Maastrichtian) of southeastern Montana. Journal of Vertebrate Paleontology 26(1):192-195.
9. Hutchison, J. H., and J. D. Archibald. 1986. Diversity of turtles across the Cretaceous/Tertiary Boundary in Northeastern Montana. Palaeogeography, Palaeoclimatology, Palaeoecology 55:1-22.
10. Johnson K. R., D. Nichols, C. Labandeira, and D. Pearson. 2000. Devastation of terrestrial ecosystems at the K-T boundary in North America: The first calibrated record of plant and animal response to the Chicxulub impact. In Catastrophic Events and Mass Extinctions: Impacts and Beyond, Vienna, pp. 85-86, LPI Contribution No. 1053, Lunar and Planetary Institute, Houston.
11. Pearson, D., A. T. Schaefer, K. R. Johnson, D. J. Nichols, and J. P. Hunter. 2002. Vertebrate biostratigraphy of the Hell Creek Formation in southwestern North Dakota and northwestern South Dakota; pp. 145-167 in J. H. Hartman, K. R. Johnson, and D. J. Nichols (eds.), The Hell Creek Formation and the Cretaceous-Tertiary boundary in the northern great plains: an integrated continental record of the end of the Cretaceous. Geological Society of America Special Paper 361.

Dinosauria from the Hell Creek Formation

LINNAEAN NAME	COMMENTS
Avisaurus archibaldi Brett-Surman and Paul 1985	An enantiornithine bird
Mononykinae incertae sedis (Hutchinson and Chiappe, 1998)	"The Montanan mononykine". A theropod closely related to, and of overall similarity to, the feathered Asian genus Mononykus
Aublysodon mirandus = ?Stygivenator	Theropod (a tooth taxon)
Aublysodon molnari = ?Stygivenator	Theropod (aka, "The Jordan Theropod")
Tyrannosaurus rex Osborn 1905 (?= Nanotyrannus lancensis Bakker, Williams and Currie, 1988) (= Albertosaurus megagracilis Paul 1988)	Possibly the most massive theropod that ever lived. Thom Carr (1999) believes that Nanotyrannus is a juvenile T. rex.
Ricardoestesia gen. Currie, Rigby and Sloan 1990:117	Theropod (a tooth/jaw taxon; note spelling***)
Ornithomimus sp.	Theropod
Ornithomimid indet.	Theropod
?Chirostenotes sp. (=?Caenagnathus)	A theropod closely related to the Asian genus Oviraptor
Troodon formosus Leidy 1856	Theropod
Troodon indet.	Theropod
Dromaeosaurus sp.	Theropod
?Velociraptor sp.	Theropod
Dromaeosaurid indet.#1	Theropod
Dromaeosaurid indet. #2	Theropod
?Thescelosaurus garbanii Morris, 1976 (=Bugenasaura infernalis? Galton, 1995)	Ornithischian (up to 12-16 feet long)
?Thescelosaurus sp.	Ornithischian
Edmontosaurus regalis	Hadrosaur ornithischian
Edmontosaurus annectens (= "Anatosaurus" annectens) (= "Trachodon")	Hadrosaur ornithischian
Anatotitan copei (= "Anatosaurus" copei) (="Trachodon")	Hadrosaur ornithischian
?Parasaurolophus walkeri	Hadrosaur ornithischian
Dracorex hogwartsia Bakker et al., 2006	"Bonehead" ornithischian. (See Bakker et al., 2006, below). May actually be an adolescent Pachycepalosaurus or Stygimoloch.
Pachycephalosaurus wyomingensis	"Bonehead" ornithischian
Stegoceras edmontonense	"Bonehead" ornithischian
Stegoceras sp.	"Bonehead" ornithischian
Stygimoloch spinifer (= Stenotholus kohleri)	"Bonehead" ornithischian
Paronychodon lacustris Cope, 1876 (nomen dubium)	A tooth taxon. "might be the dentary fang of a homalocephalid pachycephalosaur" (George Olshevsky).
Ankylosaurus indet.	Ankylosaur ornithischian
Ankylosaurus magniventris	Ankylosaur ornithischian
Ankylosaurid indet.	Ankylosaur ornithischian
?Edmontonia sp.	Nodosaur ankylosaurian
Triceratops horridus Marsh, 1889	Ceratopsian ornithischian
Torosaurus latus Marsh 1891	Ceratopsian ornithischian
Eggshell fragments (Dinosauria)	Jepsen G.L. 1931. Dinosaur egg shell fragments from Montana. Science 73(1879): 12-13. See also Horner, J. and Gorman. p. 195. Digging Dinosaurs. Workman Press.

Comments:
Troodon formosus is also found in the Two Medicine Formation (72 million years old at it's top). If T. formosus is also found in the Hell Creek Formation (~65-67 million years old), then this theropod species has a very long temporal range. It is quite possible that the Hell Creek Troodon material (teeth) will turn out to be from new species. This idea was first proposed by Currie et al. (1990).

*** Ricardoestesia was originally misspelled by the typesetter as Richardoestesia in the Currie et al. (1990) paper. George Olshevsky (1992), as first revisor, published the corrected spelling in his serial publication Mesozoic Meanderings #2 (2nd Printing).

References:

1. Various authors, 1990. Dinosaur Distributions, p. 117-118, IN Weishampel, D. B., P. Dodson, and H. Osmolska (eds.).1990. The Dinosauria. University of California Press, Berkeley.
2. Bakker, R. T., R. M. Sullivan, V. Porter, P. Larson, and S. J. Salsbury. 2006. Dracorex hogwartsia, n. gen., n. sp., a spiked, flat-headed pachycephalosaurid dinosaur from the Upper Cretaceous Hell Creek Formation of South Dakota. in Lucas, S. G. and Sullivan, R. M., eds., Late Cretaceous vertebrates from the Western Interior. New Mexico Museum of Natural History and Science Bulletin 35, p. 331–345.
3. Carr, T. D. 1999. Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria). Journal of Vertebrate Paleontology 19(3): 497-520.
4. Currie, P. J., J. K. Rigby, Jr., and R. E. Sloan. 1990. Theropod teeth from the Judith River Formation of southern Alberta, Canada, IN Carpenter, K., and P.J. Currie (eds.). Dinosaur Systematics: Perspectives and Approaches. Cambridge University Press. (information on the Hell Creek Fm. occurrence on page 117).
5. Galton, P.M. 1995. The species of the basal hypsilophodontid dinosaur Thescelosaurus Gilmore (Ornithischia; Ornithopoda) from the Late Cretaceous of North America. Neues Jahrbuch fuer Geologie und Palaeontologie. Abhandlungen, vol. 198(3):297-311.
6. Holtz, T. 1997. Internet Usenet post to sci.bio.paleontology on 4/29/1997. (regarding status of Aublysodon).
7. Hutchinson, J.R., and Chiappe, L.M. 1998. The first known Alvarezsaurid (Theropoda: Aves) from North America. Journal of Vertebrate Paleontology 18(3):447-450.
8. Olshevsky, G. 1997. Whatever happened to Trachodon?. Jeff's Journal of Dinosaur Paleontology: http://www.dinosauria.com/jdp/misc/trachodon.html (regarding taxonomic status of "Anatosaurus")
9. Olshevsky, G. 1997. Regarding the taxonomic affinity of Paronychodon lacustris. A public post to the Dinosaur Mailing list.
   
10. Sues, H-D. 1997. On Chirostenotes, a Late Cretaceous oviraptorosaur (Dinosauria: Theropoda) from western North America. Journal of Vertebrate Paleontology 17(4): 698-716.
    
11. White, P.D., D.E. Fastovsky, and P.M. Sheehan. 1998. Taphonomy and suggested structure of the dinosaurian assemblage of the Hell Creek Formation (Maastrichtian), eastern Montana and western North Dakota. Palaios, volume 13:41-51.
    

LINNAEAN NAME	COMMENTS
Sphaerochara brewsterensis	-
Tectochara sp.	-

Reference:

1. Chiment, J. 1985. Late Cretaceous and early Tertiary charophyte floras from Garfield Co., Montana. American Association for the Advancement of Science (AAAS) Annual Meeting, Program with Abstracts, New York.
   

LINNAEAN NAME	COMMENTS
Alnipollenites	-
Aquilapollenites	"Several species, many specimens". Bohor et al. (1984)
Balmeisporites	-
Cranwellia striata	-
Gunnera microreticulata	-
Kurtzipites Anderson 1960	Misspelled as "Kurzlpites" by Smit and Van der Kaars (1983, figure 2)
Liliacidites spp.	-
Pandaniidites	-
Proteacidites spp.	Misspelled as "Proteaccidites" in Bohr et al. (1984)
Tricolpites parvistriatus	-
Ulmipollenites	-
Wodehouseia spinata	-

Comments:

This rudimentary beginning to the fossil pollen list was copied from:

1. Bohor et al. 1984. Mineralogic evidence for an impact event at the Cretaceous-Tertiary Boundary. Science 224: 867-869.
   
2. Rigby, Jr. et al. 1987. Dinosaurs from the Paleocene part of the Hell Creek Formation, McCone County, Montana. Palaios 2: 296-302.
   
3. Smit and Van Der Kaars. 1983. Terminal Cretaceous Extinctions in the Hell Creek area, Montana: compatible with catastrophic extinction. Science 223:1177-1179.
   

LINNAEAN NAME	COMMENTS
**Annona? robusta	Abundant at Brownie Butte, MT
"Artocarpus" lessigiana (Lesquereux) Knowlton. TYPE. YPM-6310; YPM-6428	-
**"Celastrus" taurenensis Ward. TYPE. YPM 6223-6224	Some may be Eucommiacaea. A mixed taxonomic bag?
"Cinnamomum" lineafolia Knowlton. TYPE. YPM-6220	Included in "Ficus" affinis by L. Hickey. Belongs in Rhamnaceae (modern Buckthorns and Ceanothus). Some other specimens referred to Cinnamomum sezanensis(?) sp.), a real cinnamon bush
** "Cissus" marginata (Lesquereux) Brown. TYPE. YPM-6125; other specimens YPM 6380-6381; YPM-6433	Also spelled "marginatus". Common flora at Brownie Butte, MT.
** "Dryophyllum" subfalcatum Lesquereux. TYPE. YPM-6170; other specimens YPM 6384-6385; YPM 6382-6383	One of the most common plant taxa in the Hell Creek and Lance Formations. Common at Brownie Butte, MT. If it is close to real Dryophyllum then it is a beech/chestnut-like tree (Fagaceae). It may also be a walnut-like tree (Juglandaceae)
"Dryophyllum" tenneseensis. TYPE. YPM-6167; other specimens YPM 6356-6357	see above
**"Ficus" sp.	-
"Ficus" artocarpoides Lesquereux. TYPE. YPM-6212; other specimens YPM 6440-6441; YPM-6388; YPM-6389A	These fossil "figs" have been determined to be probable equisitalean root tubers
"Ficus" planicostata Lesquereux. TYPE. YPM-6128; other specimen YPM-6353	Synonymous with "Ficus" affinis. Probably in the Rhamnaceae (Buckthorn family)
**"Ficus trinervis	Part of the "Ficus" affinis complex
**"Juglans" leconteana	-
"Liriodendron" laramiense Ward. TYPE. YPM-6297; other specimens YPM 6358-6362	May be related to today's tulip tree (yellow poplar)
"Quercus" viburnifolia Lesquereux. TYPE. YPM-6226	Included within "Cissus" marginata. May be in the Platanaceae (American sycamore or plane tree)
"Rhamnus" cleburnii Lesquereux. TYPES. YPM 6183-6184; other specimens YPM-6390; YPM-6442	A Buckthorn look-alike.
"Vitis" stantonii (Knowlton) Brown. TYPE. YPM-6138; other specimens YPM-7042; YPM 6349-6351	This could be a real Vitus (a real grape)
**"Viburnum" sp.	-
"Ziziphus" fibrillosus YPM-6305	-
Androvettia catenulata Bell. TYPE. YPM-6267; other speciemens YPM 6386-6387	-
Araliaephyllum polevoi (Kryshtofovich) Krassilov. TYPE. YPM 6179-6182	-
Berberidaceae. TYPE. YPM-6320	Today's Barberry is a member of this family
Bisonia niemii Johnson	Broad leaf. Type specimen was found near a T. rex skeleton in S. Dakota (the "Sue" site)
?Cannabaceae. TYPES. YPM 6203-6205; Other specimen YPM-6363A	The family that includes marijuana!
Carpites ulmiformis Dorf. YPM-6172	-
Chloranthaceae. TYPES. YPM 6214-6215	-
Cissites insignis Capellini and Heer. TYPE. YPM-6318	-
Cissites lobata Dorf. TYPE. YPM-6306	May belong in Hamemelididae (subclass which includes sycamore)
Cissites puilasokensis Heer. TYPE. YPM 6311-6312	-
Coniferales YPM-8792; YPM 8820-8821	conifer
Cupressinocladus interruptus (Newberry) Schweitzer YPM-6354	-
Dilleniidae. TYPE #1. YPM-6193; TYPES #2. YPM 6286-6287	-
Dombeyopsis trivialis Lesquereux YPM-6346; YPM 6377-6379; YPM 6347-6348	-
Dombeyopsis YPM 8198-8201	-
**Dombeyopsis obtusa	In Platanales, according to Leo Hickey
Elatides longifolia (Lesquereux) Johnson. TYPE. YPM-6296	-
Erlingdorfia montana	Sycamore. (See Johnson and Stucky, 1995)
Fagaceae. TYPE. YPM-6229	Possibly related to members of today's beech family
Filicales. TYPE #1. YPM-6243; TYPE #2. YPM-6132; TYPE #3. YPM-6322; TYPE #4. YPM-6199	-
Filicites knowltonii Dorf. TYPE. YPM-6259	-
Flacourtiaceae. TYPE. YPM-6273	-
*Gingko adiantoides. TYPE. YPM-6242	The only gingko in the Hell Creek Formation; uncommon
Glyptostrobus Endlicher 1847. TYPE. YPM-6400	-
Glyptostrobus sp. #2. TYPE. YPM-6133	-
Grewiopsis saportana Lesquereux. TYPE. YPM-6126	Another generic Hamamelididae
Hamamelididae. TYPE #1. YPM-6269; TYPE #2. YPM-6146	"Witch-Hazel Family". Witch-Hazel and Sweet Gum are modern examples of this plant group.
Laurales. TYPE #1. YPM-6435; TYPES #2. YPM 6207-6210; TYPE #3. YPM-6154; TYPES #4. YPM 6293-6294; other specimen YPM-6436	Today's cinnamon and avocado trees are examples of this group
Laurophyllum wardiana (Knowlton) Dorf, 1942. YPM-6177	-
Leepierceia preartocarpoides	A broad-leaf angiosperm. (see Johnson and Stucky, 1995)
Liriodendron? YPM 7583-7585	May be related to today's tulip tree (yellow poplar)
Magnolia pulchra Ward, 1884-85[1886]. TYPE. YPM-6309	This species was thought to occur only in southern Wyoming flora, but Leo Hickey claims it is found further north in Montana and the Dakotas
Magnoliopsida. TYPE #1. YPM-6241; TYPES #2. YPM 6134-6135; TYPE #3. YPM-6307; TYPE #4. YPM-6129; TYPE #5. YPM-6127; TYPES #6. YPM 6300-6304; other specimens YPM-6429; YPM-6434	-
Marchantia pealii Knowlton. TYPES. YPM 6252-6253	-
Metasequoia sp. #2. TYPE. YPM-6158	Related to today's Dawn Redwood. Examine a fossil Metasequoia seed cone from the Hell Creek Formation
*Nilssonia yukonensis Hollick. TYPE. YPM-6295	The only Hell Creek Formation cycad. Uncommon
Onoclea hesperia Brown 1962. TYPE. YPM-6143	-
Palaeoaster inquirenda. TYPE. YPM-6131	Angiosperm. Produces LARGE seed pods. References.: Smith, U. R. 2000. Palaeoaster (Papaveraceae), the Cretaceous poppy. Ph.D. Thesis, Yale University: New Haven. Smith, U. R., and Hickey, L. J. 1994. A capsular fruit from the latest Cretaceous of the Western Interior United States. American Journal of Botany 81, 102-103.
PaleoasterYPM 8187-8194; YPM-8195; YPM-8196	See above
Paranymphaea hastata Brown YPM-6438; YPM-6430	-
Pistia corrugata Lesquereux. TYPE. YPM-6198; other specimen YPM-6431	-
**Platanophyllum sp.	-
Platanophyllum montanum (Brown) Dorf. TYPE. YPM-6176; other specimens YPM-6443; YPM 6341-6344; YPM-6352; YPM 6375-6376; YPM 6371-6372; YPM-6373	-
Porosia verrucosa Hickey. TYPE. YPM-6136	-
**Rhamnus salicifolius	Another Buckthorn look-alike. Abundant at Brownie Butte, MT
Rosaceae. TYPES. YPM 6201-6202; other specimen YPM-6365A	Family that includes today's roses, apples, cherries, almonds, etc. (a large family)
Rosidae. TYPE #1. YPM-6326; TYPE #2. YPM-6169; TYPE #3. YPM-6144	-
Sabalites sp. YPM-6439	Palm
Sapindopsis powelliana (Lesquereux) Johnson. TYPES. YPM 6246-6247	-
Sequoia sp. TYPE. YPM-6191	Most Lancian Sequoia are placed in S. artus
**Sequoites artus	-
Taxodium olrikii (Heer) Brown. TYPE. YPM-6192; Other specimens YPM 7777-7778	Related to today's Bald Cypress
Trochodendrales. TYPE. YPM-6194; Other specimen YPM-6437	-
**Trochodendroides arctica	-
Trochodendroides nebrascensis (Newberry) Dorf. TYPES. YPM 6231-6232; Other specimen YPM-6444	-
Ulmaceae. TYPE #1. YPM-6159; TYPE #2. YPM-6160	Elm?
Urticaceae. TYPES #1. YPM 6221-6222; TYPE #2. YPM-6142	Nettle family
Zingiberopsis attenuata Hickey and Peterson, 1978. TYPE. YPM-6328	Related to todays ginger plant
aff. "Dryophyllum" subfalcatum. TYPE. YPM-6255	-
aff. "Populus" nebrascensis. TYPE. YPM-6137	-
aff. "Vitis" Stantonii (Knowlton) Brown. TYPE #1. YPM-6298; TYPE #2. YPM-6288; TYPE #3. YPM-6321	-
aff. Cercidiphyllum sp. TYPE. YPM-6254	Witch-hazels and Katsura trees. Johnson (1998) notes the presence of Cercidiphyllaceae in the Formation
aff. Laurales. TYPE #1. YPM-6324; TYPE #2 YPM-6156	-
aff. Platanaceae. TYPE #1. YPM-6244;TYPES #2. YPM 6280-6281;TYPE #3. YPM-6168; TYPE #4. YPM-6162; TYPES #5. YPM 6329-6330	-
aff. Saururaceae. TYPE. YPM-6315	-
cf. "Cinnamomum" lineafolia. TYPE. YPM-6240	-
cf. "Cocculus" flabella. TYPE. YPM-6140	-
cf. Cissites acerifolia Lesquereux. TYPE. YPM-6185	-
cf. Nelumbo. TYPE #1 YPM-6316A; TYPE #2 YPM-6316B	-
cf. Pistia corrugata. TYPE. YPM-6200	Floating aquatic herb
unknown flowers. YPM-7209A	-
unknown seed. TYPE. YPM-6206	-
unknown seed. YPM-6445	-

Comments:

Dr. Kirk Johnson claims that there are no grasses, oaks, maples, or willows in the Hell Creek Formation. Ferns are uncommon in the majority of the formation, however there is a great increase in the abundance of fossil fern spores in the two centimeters of rock that directly overlies the impact fallout layer (the famous K-T boundary layer). This increase in fern spore abundance is commonly referred to as "the fern spike" (meaning that if the abundance of spores as a function of stratigraphic position were plotted out, the graph would show a spike just above the impact fallout layer). Johnson also found that the majority of the angiosperm genera in the Hell Creek Formation are now extinct. He also believes that, very roughly, 80% of the plant life died out in what is now Montana and the Dakotas at the K/T boundary.

Many of the modern plant affinities in the Hell Creek Formation (e.g., those with the prefix "aff." or with quotes around the genus name) may not in reality belong to these genera; instead they could be entirely different plants that resemble modern genera. Therefore, there is some question regarding whether the modern Populus or Juglans, as two examples, actually lived in the latest Cretaceous.

I downloaded, weeded, and compiled the majority of this plant list off the Yale-Peabody gopher server sometime around 1994-95. The fossils were collected mainly by Drs Kirk Johnson and Leo Hickey. I added a few taxa that were collected at Brownie Butte Montana by Shoemaker, but most plants are from North Dakota (Slope County) and South Dakota. "TYPE" after the binomial means that it is represented by a type specimen found in the Yale-Peabody Museum collections. "YPM" is the prefix for the Yale-Peabody Museum specimen number.
Compared to fossil plant localities in the Dakotas, relatively few specimens have been collected from Montana.

The Araucariaceae may be the source plants for AMBER in the formation. Cretaceous amber from Lebonon (135 mya - 120 mya) comes from the flora Araucaria and Agathis. I have not found any specific references regarding the source flora for the North American Hell Creek amber, so if anyone has a reference on its source, please let me know!

References:

1. Yale-Peabody Museum specimen collection gopher server, year 1994.
   
   
2. * = Johnson, K. 1997. Hell Creek Flora, pp. 300-302, in Currie, P., and K. Padian (eds.), Encyclopedia of Dinosaurs, Academic Press, 869 pages.
   
   
3. Johnson, K. R. 1998. Floristics and taphonomy of anomalous, small-leaved floras from the middle Hell Creek Formation (Late Cretaceous; late Maastrichtian), southwestern North Dakota. American Journal of Botany, Vol. 85, No.6, 1-191. Baltimore, Maryland Meeting. June 1998 Supplement-Abstracts, pg. 75, Abstract 218.
   
   
4. Johnson, K. R., and Stucky, R.K. 1995.Prehistoric Journey Robert Rinehart Publishers. 144 p.
   
   
5. ** = Also found at Brownie Butte, MT by Dr. R. E. Shoemaker.