Man on the Hill (MOTH)

The Man on the Hill (MOTH) locality of northwestern Canada has fossils that are very well preserved and have had a profound impact on the understanding of vertebrate evolution. The geology of the MOTH locality consists of fine, alternating laminae of light grey argillaceous limestone, or calcareous shale, and dark grey silt to sand-rich calcareous shale, as observed in thin section, and the characterization of the lithology for the vertebrate-bearing strata as an interlaminated argillaceous limestone and calcareous shale. The abundance of cryptic trace fossils and the presence of pyrite suggest that the intra-shelf topographic sag at MOTH had restricted circulation and was generally hypoxic (Zorn et al. 2005).[1]

The MOTH locality (62°32' N, 127°45' W) is located in the Central Mackenzie Mountains, approximately 70 km northeast of Tungsten, Northwest Territories, Canada (Hanke 2008).[2] The MOTH locality was named after a pile of rocks resembling a human sitting on a ridge (Man-on-the-Hill) (Adrain & Wilson 1994).[3] The locality is on the southwest limb of the Grizzly Bear anticline in rocks which are thought to be transitional between the Road River Formation and the Delorme Group (Adrain & Wilson 1994). Gabrielse et al. (1973)[4] provided the original description of the structural geology, lithological features, and associated invertebrate and vertebrate fossils in the measured section at MOTH. The marine rocks preserved in the Mackenzie Mountains were deposited in spatially extensive sedimentary units, including the Whittaker, Delorme, and Road River formations (Perry 1984;[5] Morrow & Geldsetzer 1988[6]) that fringed the western margin of Laurussia (the combined Laurentian and Baltic regions) during the Late Silurian and Early Devonian (Copeland 1978;[7] Chatterton & Perry 1983[8]).

References
  1. Zorn, M.E.; Caldwell, M.W.; Wilson, M.V.H., Lithological analysis of the Lower Devonian vertebrate-bearing beds at the MOTH locality, N.W.T., Canada: insights to taphonomy and depositional setting, Canadian Journal of Earth Sciences, May 2005,42 (5).
  2. Hanke G. F. 2008, Promesacanthus eppleri n. gen., n. sp., a mesacanthid (Acanthodii, Acanthodiformes) from the Lower Devonian of northern Canada. It falls within the protective boundaries of Nááts'ihch'oh National Park Reserve, making it illegal to remove any of the rocks or fossils found in the area. Geodiversitas 30 (2) : 287-302.
  3. Adrain J. M. & Wilson M. V . H. 1994. — Early Devonian cephalaspids (Vertebrata: Osteostraci: Cornuata) from the southern Mackenzie Mountains, N.W.T., Canada. Journal of Vertebrate Paleontology 14 (3): 301-319.
  4. Gabrielse H., Blusson S. L. & Roddick J. H. 1973, Geology of the Flat River, Glacier Lake, and Wrigley Lake Map-areas, District of Mackenzie and Yukon Territory. Geological Survey of Canada, Memoir 366: 1-153.
  5. Perry D. G. 1984. — Brachiopoda and biostratigraphy of the Silurian-Devonian Delorme Formation in the District of Mackenzie, the Yukon. Royal Ontario Museum, Life Sciences Contributions 138: 1-243.
  6. Morrow D. W. & Geldsetzer H. H. J. 1988, Devonian of the eastern Canadian cordillera, in McMillan N. J., Embry A. F. & Glass D. J. (eds), Devonian of the World; Proceedings of the second international symposium on the Devonian System. Volume 1, Regional Syntheses. Memoir of the Canadian Society of Petroleum Geologists 14 (1): 85-121.
  7. Copeland M. J. 1978, Early Palaeozoic ostracode assemblages, northwestern Canada. Special Paper of the Geological Association of Canada 18: 93-111.
  8. Chatterton B. D. E. & Perry D. G. 1983,Silicified Silurian odontopleurid trilobites from the Mackenzie Mountains. Palaeontographica Canadiana 1: 1-126.
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