Stuck in the mud: experimental taphonomy and computed tomography demonstrate the critical role of sediment in stabilizing the three-dimensional external morphology of arthropod carcasses during early fossil diagenesis - DRAGONFLY sessions

Exceptionally preserved fossils provide critical information on the morphology and ecology of extinct organisms, but their formation requires complex pathways that affect the process of decay in any given depositional environment. The field of experimental taphonomy has produced critical insights that allow us to better understand the physical and chemical mechanisms responsible for fossil preservation. However, taphonomic experiments designed to assess the rate of morphological information loss typically require that they are performed in artificial sea water without sediment to clearly quantify any observable changes over time. Here, we utilize micro-computed tomography to non-invasively investigate changes in carcasses of the branchiopod crustacean Triops longicaudatus for over a year of post-burial decay. After 64 weeks, specimens are still detectable as three-dimensional low-density volumes that capture various external morphological features in life position, including the body ou..., Taxon selection  
Branchiopod crustaceans Triops longicaudatus (Order Notostraca) were grown according to the instructions from the commercially available Toyops’ Triops kit until they reached maturity and desired size of 3-5cm at three weeks after hatching. All specimens were euthanized by refrigeration, being frozen for 3 hours, and then thawed in a refrigerator overnight.  
Sediment collection and preparation  
Fresh estuarine sediment was collected from Belle Isle Marsh Reservation in Boston, Massachusetts. At low tide, one 5-gallon bucket of sediment was collected from each of the two 0.5-0.75 meters deep pits, one located one meter toward the stream from the peak of high tide (42.392208, -70.991179) and another 5 meters closer to the center of the tidal stream (42.392157, -70.991088). The sediment was collected from dark gray fine grain mud with a strong sulfidic smell, indicating the presence of sulfate-reducing bacteria in an anoxic environment. Lar..., , ### \*\*Note to users:\*\*

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