Climactichnites:

Climactichnites is an enigmatic, late Cambrian fossil formed on or within sandy tidal flats around 510 million years ago. It is usually interpreted as the trace fossil of a slug-like organism, thought to have moved by sliding over a mucus-rich slime trail or burrowing into the sediment.

Morphology

Climactichnites consists of undulating bars and furrows oriented at an angle to the direction of travel^[1]. The fossils range from 2 to 15cm in width,^[2]^[3] and may exceed ten feet in length, making them far larger than most invertebrate trace fossils.^{[verification needed]}

Interpretation

Climactichnites as a trace fossil

The traditional interpretation of Climactichnites suggests that it represents the trackway of an animal. This would make it the earliest evidence of organisms moving about on the land.^[4] It is now commonly believed that the traces that lacked lateral ridges were burrows (Getty and Hagadorn, 2008). Those with lateral ridges are thought to have been produced as the animal crawled over and processed the wet sand to obtain food. While the identity of the animal is still conjectural, it may have been a large slug-like animal. The binding effect of microbial mounds on the sediment surface is believed to have contributed to the exceptional preservation of Climactichnites tracks. ^[5]

Climactichites as a body fossil

Pointing to the fact that some Climactichnites tracks disturb the underlying structures, such as ripple marks and other Climactichnites, to a lesser extent than one might expect from an organism plowing its way across the surface, one team of researchers (Damrow et al., 2001) questioned whether Climactichnites may instead be a body fossil of a strap-like organism. This theory has not been supported by subsequent researchers, who argue that modern soft-bodied organisms exhibit folding, twisting, tearing or transport when washed ashore. This is observed in jellyfish fossils from beds close to Climactichnites, so would be expected in at least some of the Climactichnites if they were indeed stranded organisms. Other lines of evidence also refute the Climactichnites as body fossil theory (see Getty, 2007, page 2).^[6]

References

^ Getty, P.R.; Hagadorn, J.W. (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, doi:10.1666/08-004.1
^ Getty, P.R. (2005). "Small Climactichnites Trackways: Their Abundance And Implications For Trackmaker Physiology". 2005 Salt Lake City Annual Meeting, http://gsa.confex.com/gsa/2005AM/finalprogram/abstract_93004.htm. Retrieved on 2 June 2008.
^ Damrow, D.F.; Lipps, J.H.; Gershwin, L. (2001). "Is Climactichnites Really A Trace Fossil?". GSA Annual Meeting, November 5-8, 2001, http://gsa.confex.com/gsa/2001AM/finalprogram/abstract_28754.htm. Retrieved on 2 June 2008.
^ MacNaughton, R.B.; Cole, J.M.; Dalrymple, R.W.; Braddy, S.J.; Briggs, D.E.G.; Lukie, T.D. (2002). "First steps on land: Arthropod trackways in Cambrian-Ordovician eolian sandstone, southeastern Ontario, Canada". Geology 30 (5): 391-394. doi:10.1130/0091-7613(2002)030<0391:FSOLAT>2.0.CO;2.
^ Getty, P.R. (2006). "Producing And Preserving Climactichnites". 2006 Philadelphia Annual Meeting, http://gsa.confex.com/gsa/2006AM/finalprogram/abstract_111068.htm. Retrieved on 2 June 2008.
^ Patrick R. Getty (2007). Paleobiology of the Climactichnites Trackmaker: An Enigmatic Late Cambrian Animal Known Only from Trace Fossils, http://scholarworks.umass.edu/theses/19/.

Climactichnites

Contents

Morphology

Interpretation

Climactichnites as a trace fossil

Climactichites as a body fossil

References

External links