Protichnites

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Protichnites
Temporal range: 530.0–457.5 
Ma
The trackway Protichnites from the Cambrian of Blackberry Hill, Wisconsin
Trace fossil classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda (?)
Ichnogenus: †Protichnites
Owen, 1852
Ichnospecies[1]
  • †Protichnites alternans
  • †Protichnites eremita
  • †Protichnites latus
  • †Protichnites lineatus
  • †Protichnites multinotatus
  • †Protichnites octo-notatus
  • †Protichnites septem-notatus

Protichnites is an

arthropods
. It consists of two rows of tracks and a medial furrow between the two rows. This furrow, which may be broken, set at an angle, and of varying width and depth, is thought to be the result of the tail region contacting the substrate.

The first footprints on land

Sir

Dinosauria”, based Protichnites on trackways that were shipped to him from the Cambrian Potsdam Sandstone of Quebec.[2] He was correct in recognizing that these were the oldest known footprints on land, having been produced in intertidal and supratidal environments during what would now be called Cambrian times.[3]

The Protichnites makers

Owen first thought that these trackways were made by tortoises,

mandibulates.[4] Fossils that clearly tie euthycarcinoids to Protichnites were then found at Blackberry Hill.[5]

It is possible that other extinct arthropods, such as members of the Aglaspidida, may also have produced some of these trackways. Trilobites have been suggested as well; however, no aglaspidids or trilobites have been found thus far in the strata that contain this ichnogenus. Similar trackways are present in post-Cambrian strata; however, those are seldom referred to as Protichnites.

Behavior

It has been suggested that one form of Protichnites, P. eremita Form 1, may have been produced by an ambulating pair of individuals, as in amplexus. In this form, the medial furrow is discontinuous and each section is set at an angle, such that the series of medial imprints have a shingled appearance, as might result if the female were displacing her tail to minimize its interference with external fertilization. A second set of medial imprints observed in Form 1 is postulated to have been produced by the tail region of the male of the pair.[5] Protichnites eremita was originally interpreted as early evidence of hermit crab-like behavior.[6] It has also been suggested that some P. eremita may have been produced by distressed individuals attempting to return to a body of water after being stranded during high tide, which was more extensive than today due to the moon being closer to Earth in Cambrian times.[7]

Relationship with Diplichnites

Differing only in the presence or absence of a medial furrow, Protichnites and Diplichnites trackways could both be produced by the same individual animal. In cases where the feet penetrate the sediment more deeply than does the tail, Diplichnites could be created on the underlying layer while Protichnites is being produced on the surface.[8][9]

References

  1. ^ a b Owen, 1852
  2. ^ a b Owen, 1851
  3. ^ a b Collette and Hagadorn, 2010
  4. ^ Ortega-Hernandez et al, 2010
  5. ^ a b Collette et al., 2012
  6. ^ Hagadorn and Seilacher, 2009
  7. ^ Braddy and Gass, 2022
  8. ^ Goldring and Seilacher, 1971
  9. ^ Hoxie, 2005

Further reading

External links
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