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Swimming reptiles make their mark in the Early Triassic

Date:
February 9, 2015
Source:
Geological Society of America
Summary:
Vertebrate tracks provide valuable information about animal behavior and environments. Swim tracks are a unique type of vertebrate track because they are produced underwater by buoyant trackmakers, and specific factors are required for their production and subsequent preservation. Early Triassic deposits contain the highest number of fossil swim track occurrences worldwide compared to other epochs, and this number becomes even greater when epoch duration and rock outcrop area are taken into account.
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This image shows a swim traceway from Capitol Reef National Park.
Credit: Tracy J. Thomson and Mary L. Droser, Geology, 5 Feb. 2015.

Vertebrate tracks provide valuable information about animal behavior and environments. Swim tracks are a unique type of vertebrate track because they are produced underwater by buoyant trackmakers, and specific factors are required for their production and subsequent preservation. Early Triassic deposits contain the highest number of fossil swim track occurrences worldwide compared to other epochs, and this number becomes even greater when epoch duration and rock outcrop area are taken into account.

This spike in swim track occurrences suggests that during the Early Triassic, factors promoting swim track production and preservation were more common than at any other time. Coincidentally, the Early Triassic period follows the largest mass extinction event in Earth's history, and the fossil record indicates that a prolonged period of delayed recovery persisted throughout this time period.

During this recovery interval, sediment mixing by animals living within the substrate was minimal, especially in particularly stressful environments such as marine deltas. The general lack of sediment mixing during the Early Triassic was the most important contributing factor to the widespread production of firm-ground substrates ideal for recording and preserving subaqueous trace fossils like swim tracks.


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Journal Reference:

  1. T. J. Thomson, M. L. Droser. Swimming reptiles make their mark in the Early Triassic: Delayed ecologic recovery increased the preservation potential of vertebrate swim tracks. Geology, 2015; DOI: 10.1130/G36332.1

Cite This Page:

Geological Society of America. "Swimming reptiles make their mark in the Early Triassic." ScienceDaily. ScienceDaily, 9 February 2015. <www.sciencedaily.com/releases/2015/02/150209143531.htm>.
Geological Society of America. (2015, February 9). Swimming reptiles make their mark in the Early Triassic. ScienceDaily. Retrieved May 23, 2017 from www.sciencedaily.com/releases/2015/02/150209143531.htm
Geological Society of America. "Swimming reptiles make their mark in the Early Triassic." ScienceDaily. www.sciencedaily.com/releases/2015/02/150209143531.htm (accessed May 23, 2017).

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