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Origins of microfossil bonebeds: insights from the Upper Cretaceous Judith River Formation of north-central Montana

  • Raymond R. Rogers (a1) and Mara E. Brady (a1)

Microfossil bonebeds are multi-individual accumulations of disarticulated and dissociated vertebrate hardparts dominated by elements in the millimeter to centimeter size range (≤75% of bioclasts ≤5 cm maximum dimension). Modes of accumulation are often difficult to decipher from reports in the literature, although predatory (scatological) and fluvial/hydraulic origins are typically proposed. We studied the sedimentology and taphonomy of 27 microfossil bonebeds in the Campanian Judith River Formation of Montana in order to reconstruct formative histories. Sixteen of the bonebeds examined are hosted by fine-grained facies that accumulated in low-energy aquatic settings (pond/lake microfossil bonebeds). Eleven of the bonebeds are embedded in sandstones that accumulated in ancient fluvial settings (channel-hosted microfossil bonebeds). In lieu of invoking separate pathways to accumulation based on facies distinctions, we present a model that links the accumulation of bioclasts in the two facies. We propose that vertebrate material initially accumulates to fossiliferous levels in ponds/lakes and is later reworked and redeposited as channel-hosted assemblages. This interpretation is grounded in reasonable expectations of lacustrine and fluvial depositional systems and supported by taphonomic data. Moreover, it is consistent with faunal data that indicate that channel-hosted assemblages and pond/lake assemblages are similar with regard to presence/absence and rank-order abundance of taxa.

This revised model of bonebed formation has significant implications for studies of vertebrate paleoecology that hinge on analyses of faunal data recovered from vertebrate microfossil assemblages. Pond/lake microfossil bonebeds in the Judith River record are preserved in situ at the scale of the local paleoenvironment, with no indication of postmortem transport into or out of the life habitat. Moreover, they are time-averaged samples of their source communities, which increases the likelihood of capturing both ecologically abundant species and more rare or transient members of the paleocommunity. These attributes make pond/lake microfossil bonebeds excellent targets for paleoecological studies that seek to reconstruct overall community membership and structure. In contrast, channel-hosted microfossil bonebeds in the Judith River record are out of place from a paleoenvironmental perspective because they are reworked from preexisting pond/lake assemblages and redeposited in younger channel facies. However, despite a history of exhumation and redeposition, channel-hosted microfossil bonebeds are preserved in relatively close spatial proximity to original source beds. This taphonomic reconstruction is counter to the commonly held view that microfossil bonebeds are biased samples that have experienced long-distance transport and significant hydrodynamic sorting.

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S. T. Abbott 1998. Transgressive systems tracts and onlap shellbeds from mid-Pleistocene sequences, Wanganui Basin, New Zealand. Journal of Sedimentary Research 68:253268.

J. L. Allulee , and S. M. Holland 2005. The sequence stratigraphic and environmental context of primitive vertebrates: Harding sandstone, Upper Ordovician, Colorado, USA. Palaios 20:518533.

S. Argast , J. O. Farlow , and R. M. Gabet 1987. Transport-induced abrasion of fossil reptilian teeth—implications for the existence of Tertiary dinosaurs in the Hell Creek Formation, Montana. Geology 15:927930.

A. K. Behrensmeyer 1988. Vertebrate preservation in fluvial channels. Palaeogeography, Palaeoclimatology, Palaeoecology 63:183189.

R. W. Blob 1997. Relative hydrodynamic dispersal potentials of soft-shelled turtle elements: implications for interpreting skeletal sorting in assemblages of non-mammalian terrestrial vertebrates. Palaios 12:151164.

R. W. Blob , M. T. Carrano , R. R. Rogers , C. A. Forster , and N. R. Espinoza 2001. A new fossil frog from the Upper Cretaceous Judith River Formation of Montana. Journal of Vertebrate Paleontology 21:190194.

T. M. Bown , and M. J. Kraus 1981. Vertebrate fossil-bearing paleosol units (Willwood Formation, Lower Eocene, Northwest Wyoming, U.S.A.): implications for taphonomy, biostratigraphy, and assemblage analysis. Palaeogeography, Palaeoclimatology, Palaeoecology 34:3156.

C. E. Brett 1995. Sequence stratigraphy, biostratigraphy, and taphonomy in shallow marine environments. Palaios 10:597616.

D. B. Brinkman 1990. Paleoecology of the Judith River Formation (Campanian) of Dinosaur Provincial Park, Alberta, Canada: evidence from vertebrate microfossil localities. Palaeogeography, Palaeoclimatology, Palaeoecology 78:3754.

D. B. Brinkman , A. P. Russell , D. A. Eberth , and J. Peng 2004. Vertebrate palaeocommunities of the lower Judith River Group (Campanian) of southeastern Alberta, Canada, as interpreted from microfossil assemblages. Palaeogeography, Palaeoclimatology, Palaeoecology 213:295313.

A. D. Buscalioni , M. A. Fregenal , A. Bravo , F. J. Poyato-Ariza , B. Sanchíz , A. M. Báez , O. Cambra Moo , C. Martín Closas , S. E. Evans , and J. Marugán Lobón 2008. The vertebrate assemblage of Buenache de la Sierra (Upper Barremian of Serrania de Cuenca, Spain) with insights into its taphonomy and palaeoecology. Cretaceous Research 29:687710.

M. T. Carrano , and J. Velez-Juarbe 2006. Paleoecology of the Quarry 9 vertebrate assemblage from Como Bluff, Wyoming (Morrison Formation, Late Cretaceous). Palaeogeography, Palaeoclimatology, Palaeoecology 237:147159.

A. Citterio , and H. Piégay 2009. Overbank sedimentation rates in former channel lakes: characterization and control factors. Sedimentology 56:461482.

P. Dodson 1971. Sedimentology and taphonomy of Oldman Formation (Campanian), Dinosaur Provincial Park, Alberta (Canada). Palaeogeography, Palaeoclimatology, Palaeoecology 10:2174.

G. J. Dyke , and D. V. Malakhov 2004. Abundance and taphonomy of dinosaur teeth and other vertebrate remains from the Botobynskaya Formation, north-east Aral Sea region, Republic of Kazakhstan. Cretaceous Research 25:669674.

D. A. Eberth 1990. Stratigraphy and sedimentology of vertebrate microfossil sites in the uppermost Judith River formation (Campanian), Dinosaur Provincial Park, Alberta, Canada. Palaeogeography, Palaeoclimatology, Palaeoecology 78:136.

D. A. Eberth , and A. P. Hamblin 1993. Tectonic, stratigraphic, and sedimentologic significance of a regional discontinuity in the upper Judith River Group (Belly River wedge) of southern Alberta, Saskatchewan, and northern Montana. Canadian Journal of Earth Sciences 30:174200.

D. A. Eberth , M. Shannon , and B. G. Noland 2007. A bonebeds database: classification, biases and patterns of occurrence. Pp. 103219in Rogers et al. 2007.

J. W. Eckblad , N. L. Peterson , K. Ostlie , and A. Tempte 1977. The morphometry, benthos, and sedimentation rates of a floodplain lake in Pool 9 of the upper Mississippi River. American Midland Naturalist 97:433443.

A. R. Fiorillo , K. Padian , and C. Musikasinthorn 2000. Taphonomy and depositional setting of the Placerias quarry (Chinle Formation: Late Triassic, Arizona). Palaios 15:373386.

B. Z. Foreman , R. R. Rogers , A. L. Deino , K. R. Wirth , and J. T. Thole 2008. Geochemical characterization of bentonite beds in the Two Medicine Formation (Campanian, Montana), including a new 40Ar/39Ar age. Cretaceous Research 29:373385.

H. C. Fricke , R. R. Rogers , R. Backlund , C. N. Dwyer , S. Echt 2008. Preservation of stable isotope signals in dinosaur remains, and environmental gradients of the Late Cretaceous of Montana and Alberta. Palaeogeography, Palaeoclimatology, Palaeoecology 266:1327.

J. W. Gibbons , C. T. Winne , D. E. Scott , J. D. Willison , X. Glaudas , K. M. Andrews , B. D. Todd , L. A. Fedewa , L. Wilkison , R. N. Tsaliagos , S. J. Harper , J. L. Greene , T. D. Tuberville , B. S. Metts , M. E. Dorcas , J. P. Nestor , C. A. Young , T. Akre , R. N. Reed , K. A. Buhlmann , J. Norman , D. A. Croshaw , C. Hagen , and B. B. Rothermel 2006. Remarkable amphibian biomass and abundance in an isolated wetland: implications for wetland conservation. Conservation Biology 20:14571465.

J. L. Gillespie , C. S. Nelson , and S. D. Nodder 1998. Post-glacial sea-level control and sequence stratigraphy of carbonate-terrigenous sediments, Wanganui Shelf, New Zealand. Sedimentary Geology 122:245266.

M. B. Goodwin , and A. L. Deino 1989. The first radiometric ages from the Judith River Formation (Late Cretaceous), Hill County, Montana. Canadian Journal of Earth Sciences 26:13841391.

G. Haynes 1988. Mass deaths and serial predation: comparative taphonomic studies of modern large mammal death sites. Journal of Archaeological Science 15:219235.

A. P. Hunt 1991. Integrated vertebrate, invertebrate and plant taphonomy of the Fossil Forest Area (Fruitland and Kirtland Formations – Late Cretaceous), San Juan County, New Mexico, USA. Palaeogeography, Palaeoclimatology, Palaeoecology 88:85107.

H. A. Jamniczky , D. B. Brinkman , and A. P. Russell 2003. Vertebrate microsite sampling: how much is enough? Journal of Vertebrate Paleontology 23:725734.

D. J. Jerolmack , and C. Paola 2007. Complexity in a cellular model of river avulsion. Geomorphology 91:259270.

C. K. Khajuria , and G. V. R. Prasad 1998. Taphonomy of a Late Cretaceous mammal-bearing microvertebrate assemblage from the Deccan inter-trappean beds of Naskal, peninsular India. Palaeogeography, Palaeoclimatology, Palaeoecology 137:153172.

S. M. Kidwell 1993. Influence of subsidence on the anatomy of marine siliciclastic sequences and on the distribution of shell and bone beds. Journal of the Geological Society, London 150:165167.

S. M. Kidwell , and K. Flessa 1996. The quality of the fossil record: populations, species, and communities. Annual Review of Earth and Planetary Sciences 24:433464.

S. M. Kidwell , and S. M. Holland 1991. Field description of coarse bioclastic fabrics. Palaios 6:426434.

S. M. Kidwell , F. T. Fürsich , and T. Aigner 1986. Conceptual framework for the analysis and classification of fossil concentrations. Palaios 1:228238.

A. E. Koenig , R. R. Rogers , and C. N. Trueman 2009. Visualizing fossilization using laser ablation-inductively coupled plasma-mass spectrometry maps of trace elements in Late Cretaceous bones. Geology 37:511514.

Y. Kondo , S. T. Abbott , A. Kitamura , P. J. J. Kamp , T. R. Naish , T. Kamataki , and G. S. Saul 1998. The relationship between shellbed type and sequence architecture: examples from Japan and New Zealand. Sedimentary Geology 122:109128.

F. Laudet , and N. Selva 2005. Ravens as small mammal bone accumulators: first taphonomic study on mammal remains as raven pellets. Palaeogeography, Palaeoclimatology, Palaeoecology 226:272286.

J. Leidy 1860. Extinct vertebrata from the Judith River and Great Lignite Formations of Nebraska. Transactions of the American Philosophical Society, new series 11:139154

D. L. Lofgren , C. L. Hotton , and A. C. Runkel 1990. Reworking of Cretaceous dinosaurs into Paleocene channel deposits, upper Hell Creek Formation, Montana. Geology 18:874877.

M. C. Maas 1985. Taphonomy of a late Eocene microvertebrate locality, Wind River Basin, Wyoming (USA). Palaeogeography, Palaeoclimatology, Palaeoecology 52:123142.

J. H. S. Macquaker 1994. Paleoenvironmental significance of bone-beds in organic-rich mudstone successions—an example from the Upper Triassic of South-West Britain. Zoological Journal of the Linnean Society 112:285308.

D. F. Mayhew 1977. Avian predators as accumulators of fossil mammal material. Boreas 6:2531.

M. C. McKenna 1962. Collecting small fossils by washing and screening. Curator 5:221235.

J. Mellett 1974. Scatalogical origins of microvertebrate fossil accumulations. Science 185:349350.

A. Prieto-Marquez 2005. New information on the cranium of Brachylophosaurus canadensis (Dinosauria, Hadrosauridae); with a revision of its phylogenetic position. Journal of Vertebrate Paleontology 25:144156.

N. D. Pyenson , R. B. Irmis , J. H. Lipps , L. G. Barnes , E. D. Mitchell Jr., and S. A. McLeod 2009. Origin of a widespread marine bonebed deposited during the middle Miocene Climatic Optimum. Geology 37:519522.

M. E. Räsänen , J. S. Salo , and H. Jungner 1991. Holocene floodplain lake sediments in the Amazon: 14C dating and palaeocological use. Quaternary Science Reviews 10:363372.

R. R. Rogers 1998. Sequence analysis of the upper Cretaceous Two Medicine and Judith River formations, Montana: nonmarine response to the Claggett and Bearpaw marine cycles. Journal of Sedimentary Research 68:615631.

R. R. Rogers , and S. M. Kidwell 2000. Associations of vertebrate skeletal concentrations and discontinuity surfaces in terrestrial and shallow marine records: a test in the Cretaceous of Montana. Journal of Geology 108:131154.

R. R. Rogers , D. W. Krause , and K. Curry Rogers 2003. Cannibalism in the Madagascar dinosaur Majungatholus atopus. Nature 422:515518.

R. R. Rogers , D. A. Eberth , and A. R. Fiorillo 2007. Bonebeds: genesis, analysis, and paleobiological significance. University of Chicago Press, Chicago.

M. Ryan , A. P. Russell , and D. A. Eberth 2001. The taphonomy of a Centrosaurus (Ornithischia: Certopsidae) bone bed from Dinosaur Park Formation (Upper Campanian), Alberta, Canada, with comments on cranial ontogeny. Palaios 16:482506.

J. T. Sankey 2001. Late Campanian southern dinosaurs, Aguja Formation, Big Bend, Texas. Journal of Paleontology 75:208215.

D. N. Schmitt , and K. E. Juell 1994. Toward the identification of coyote scatalogical faunal accumulations in archaeological contexts. Journal of Archaeological Science 21:249262.

P. Shipman 1981. Applications of scanning electron-microscopy to taphonomic problems. Annals of the New York Academy of Sciences 376:357385.

R. Slingerland , and N. D. Smith 2004. River avulsions and their deposits. Annual Review of Earth and Planetary Sciences 32:257285.

R. Srivastava , and K. Kumar 1996. Taphonomy and palaeoenvironment of the middle Eocene rodent localities of northwestern Himalaya, India. Palaeogeography, Palaeoclimatology, Palaeoecology 122:185211.

R. C. Terry 2004. Owl pellet taphonomy: a preliminary study of the post-regurgitation history of pellets in a temperate forest. Palaios 19:497506.

R. G. Thomas , D. G. Smith , J. M. Wood , J. Visser , E. A. Calverly Range , and E. Koster 1987. Inclined heterolithic stratification: terminology, description, interpretation, and significance. Sedimentary Geology 53:123179.

J. Trapani 1998. Hydrodynamic sorting of avian skeletal remains. Journal of Archaeological Science 25:477487.

J. S. Tweet , K. Chin , D. R. Bramen , and N. L. Murphy 2008. Probable gut contents within a specimen of Brachylophosaurus canadensis (Dinosauria, Hadrosauridae) from the Upper Cretaceous Judith River Formation of Montana. Palaios 23:624635.

A. G. van der Valk 2006. The biology of freshwater wetlands. Oxford University Press, New York.

K. Vasileiadou , J. J. Hooker , and M. E. Collinson 2009. Paleocommunity reconstruction and accumulation of micromammalian remains (late Eocene, southern England). Palaios 24:553567.

R. G. Wetzel 2001. Limnology: lake and river ecosystems, 3d ed. Academic Press, San Diego.

L. E. Wilson 2008. Comparative taphonomy and paleoecological reconstruction of two microvertebrate accumulations from the Late Cretaceous Hell Creek Formation (Maastrichtian), eastern Montana. Palaios 23:289297.

R. G. Wolff 1973. Hydrodynamic sorting and ecology of a Pleistocene mammalian assemblage from California (U.S.A.). Palaeogeography, Palaeoclimatology, Palaeoecology 13:91101.

J. M. Wood , R. G. Thomas , and J. Visser 1988. Fluvial processes and vertebrate taphonomy: the Upper Cretaceous Judith River Formation, south central Dinosaur Provincial Park, Alberta, Canada. Palaeogeography, Palaeoclimatology, Palaeoecology 66:127143.

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