Specimen 6 - Same sandstone as produced the Protichnites trackways mentioned in my blog posting from July 9, 2013 - Likely the Nepean Formation of the Potsdam Group
The specimen is about three feet wide and over four feet long. The photograph was taken using the zoom feature on my camera.
In the upper left corner the chevron pattern and absence of lateral ridges suggest that this could be the burrowing trace fossil Climactichnites youngi as the bars in the photograph compare favourably with the bar bifurcations in Figures 11 A & B in Getty and Hagadorn, 2009, with Figures 23, 41 and 48 in Yochelson and Fedonkin, 1993, and with the photographs of Climactichnites youngi in Figures 3.B and 3.C in Seilacher and Hagadorn 2010. Another interpretation is that the outcrop records wave interference ripples. (Interfering waves can make just about any pattern, including chevrons. See for example figure 3.C in Hagadorn and Belt, 2008 .)
I expect that most people would want to get a closer look at the specimen before making a positive identification. Unfortunately this specimen is at the top of an unstable blast pile at an active quarry, doesn’t meet my three basic criteria for collecting (1. Can I lift it; 2. Will it fit in the trunk of a Hyundai Accent; 3. Can I park my car close enough that I can carry it to the car), and will probably be crushed into gravel by the middle of next week.
Specimen 7 - Greyish, pink and buff sandstone, a loose specimen, found where the Hannawa Falls Member of the Covey Hill Formation of the Potsdam Group outcrops
This is interesting as it looks like a trackway, lacks chevrons, arguably has a ridge at each edge (but not the prominent ridges for Climactichnites wilsoni), but the rock may not be the Nepean Formation. It was a loose specimen found in a part of a quarry where only the Hannawa Falls Member of the Potsdam outcrops. The trackway is consistently 5 inches (12 cm) wide and compares favourably with the photographs of Climactichnites youngi in figure 3.B and 3.C in Seilacher and Hagadorn 2010. If it is Climactichnites, and the rock is not Nepean Formation, then it is out of time as all previous specimens of Climactichnites from the Potsdam Group have been found in the Nepean Formation or the equivalent Cairnside in Quebec or Keeseville in New York State. The specimen lacks barred chevrons, but Getty and Hagadorn 2008 define Climactichnites youngi as “Burrows occurring within beds (may be inclined to and crosscut bedding) or at bed interfaces, consisting of undulating bars and furrows that are often oriented at a high angle to the direction of travel. Lateral ridges absent.” and provide the description “Transverse bars straight, sinusoidal, V-, U-, or stitch-shaped. Straight bars can be perpendicular or at an angle to direction of travel; V- and U-shaped bars most often open in direction of travel. Bars often exhibit bifurcation and sometimes have backwards-pointing lateral extensions ....”
Sir William Logan originally proposed that the Climactichnites wilsoni trackway was produced by "some species of giant mollusc" (Logan, 1860) and "a species of mollusk" (Logan, 1863); a view that is now commonly accepted. Most now agree that a molluscan origin appears likely.
Specimen 8 - Greyish purple sandstone, a loose specimen, the Hannawa Falls Member of the Covey Hill Formation of the Potsdam Group, the same sandstone as Specimens 1 and 2 from my last blog posting
This meandering pattern compares favourably with the meandering burrows of slug-like bulldozers that others have found in the Cambrian. (Under mat mining?)
Christopher Brett
Perth, Ontario
References and Suggestions for Further Reading:
Ellis L. Yochelson and Mikhail A. Fedonkin, 1993,
Paleobiology of Climactichnites, an Enigmatic Late Cambrian Fossil
Smithsonian Contributions to Paleobiology • Number 74
Smithsonian Institution Press ,Washington, D.C. 1993
http://www.sil.si.edu/smithsoniancontributions/Paleobiology/pdf_lo/SCtP-0074.pdf
Patrick Ryan Getty and J. Whitey Hagadorn, 2008,
Reinterpretation of Climactichnites Logan 1860 to Include Subsurface Burrows, and Erection of Musculopodus for Resting Traces of the Trailmaker
Journal of Paleontology 82(6):1161-1172.
Patrick Ryan Getty and J. Whitey Hagadorn, 2009,
Paleobiology of the Climactichnites Tracemaker, Paleontology, Volume 52, pp. 753-778
James W. Hagadorn and Edward S. Belt (2008),
Stranded in Upstate New York: Cambrian Scyphomedusae from the Potsdam Sandstone, Palaios, v. 23, p. 424–441, doi:10.2110/palo.2006.p06-104r
Adolf Seilacher and J. Whitey Hagadorn 2010
Early Molluscan Evolution: Evidence from the Trace Fossil Record
PALAIOS, September 2010, v. 25, p. 565-575,
doi: http://dx.doi.org/10.2110/palo.2009.p09-079r
M. Gabriela Mángano and Luis A. Buatois, 2015,
The trace-fossil record of tidal flats through the Phanerozoic: Evolutionary innovations and faunal turnover, in McIlroy, D., ed., ICHNOLOGY: Papers from ICHNIA III:Geological Association of Canada, Miscellaneous Publication 9, p. 157-177
Sören Jensen, Luis A. Buatois and M. Gabriela Mángano , 2013,
Testing for palaeogeographical patterns in the distribution of Cambrian trace fossils, Chapter 5 in Early Palaeozoic Biogeography and Palaeogeography, Geological Society, London, Memoirs 2013, volume 38, p. 45-58
doi: 10.1144/M38.5
Sir William E. Logan, 1860,
On the Tracks of an Animal lately found in the Potsdam Formation, read before the Natural History Society of Montreal in June, 1860, published in volume V of The Canadian Naturalist and Geologist, Pages 279-285
Sir William E. Logan, 1863,
Geology of Canada, Geological Survey of Canada, Report of Progress from its commencement to 1863, at pages 107-108,
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