Climactichnites

Climactichnites wilsoni

The name Climactichnites is an Ichnogenus for the putative tracks (epifaunal trackways), not the name of the track makers life form

Size: about 18 by 20 feet; thickness and tonnage undetermined

Never heard of a Climactichnites, well, join the club. Not many people have, despite its scientific description in 1860 by Sir William Logan. The pictures below show a huge portion of a bedding plane absolutely loaded Climactichnites. When the photos were taken in 2004, this was the floor of a portion of the working flagstone quarry. For perspective, the fossil area measures about 18 by 20 feet. This ichnofossil normally has two parallel ridges separated by chevron-shaped raised cross bars that has often been described as motorcycle tracks; the ridges are sometimes absent, or of varied prominence. The variable width is about four inches on average. Some of are short, and some are many feet long. Some are straight, and others are curved, or even sharply curved.

The fossil sites in Wisconsin and Canada where Climactichnites are found were tidal sandflats during upper Cambrian time. As such, the ichnofossils provide the oldest known evidence of animal terrestrial colonization of Earth in the fossil record -- the first footprints on land.

Some scientists theorize that Climactichnites was made by an animal twice as long as wide having a strongly muscled underside with oblique rows of cilia and lateral flaps. The cilia may have been used to sort through sand for microorganisms and its lateral wings to grip for locomotion. In the process of feeding, sand was shoved into the conspicuous periodic

rows. The flaps may also have been used for swimming. Since Climactichnites is found on bedding surfaces with ripple marks and mud cracks, it probably spent most of its life moving across the tidal sand flats that were at least periodically above the water.

While long considered a Molusc trail (i.e., a large sea slug, or opisthobranchs), others have postulated it to be a body fossils of a large, strap-like floating zooplankter, which would help to explain how the tracks are often found to overlap in a manner that those above did not destroy those below during fossilization. Getty has recently postulated that what saved the tracks from destruction by wave action was a overlying microbial mats. Indeed, microbial sedimentary structures, such as domal sand buildups (i.e., sand stromatolites) are sometimes found in association with Climactinites in the quarry.

Climactichnites remains enigmatic. Was it a slug making the first animal footprints on

land as it meandered in the surf munching on microbial mats? Or, was it a zooplankter that floated ashore, and lured the maker of the Protichnites arthropod trackways onshore to munch on it.

There are many images (warning, these are all large fossil images) of this large climatichnites below, from different perspectives and distances. When the sun is directly overhead in the quarry, the fossils are subtle. When shadows are long, however, as was the case when these pictures were taken, the fossils jump out of the sandstone.

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