During three field campaigns from 2017 to 2019, Fernando Valencia together with Gustavo Valencia and colleagues from the Texas A&M University (Dr. Juan Laya and Dr. Mike Pope) have been describing several stratigraphic sections where the highly-bioturbated Buda Limestone crops out. Most outcrops are distributed along the central and west Texas regions (Fig. 1). The main focus of Fernando’s project is to define the sedimentological model of the Buda Limestone in west-central Texas and the implications of the pervasive bioturbation in the process of porosity creation. Preliminary observations recognized a strong influence of the trace fossils in the diagenetic processes of the carbonate succession (Fig. 2).

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Figure 1. Sharp contact between the Buda Limestone and the overlying Eagle Ford Gp. along the U.S. Highway 90 in the Comstock – Texas area.

Figure 2. Detail of intra-burrow secondary porosity developed in a Thalassinoides isp. Upper-Cretaceous Buda Limestone (west Texas).

By Fernando Valencia

Recent research by Dr. Mángano and Dr. Buatois, performed in collaboration with researchers from around the world, suggests that organisms were capable of movement much earlier than previously thought.

Around 80 specimens of 1 to 6 millimetre-sized, pyritized, string-shaped structures were collected from the Francevillian Basin in Gabon and subjected to a slew of analyses in order to determine their origin. The structures were found to have been formed within the sediment, lithified prior to compaction with open pore spaces, and filled with pyrite formed from sulfide generated by sulfate-reducing microorganisms.

After a careful comparison with several abiotic structures such as syneresis cracks and microbial mat roll-ups, as well as various biotic strucutres, it was determined that these structures were likely produced by a motile organism. It is unlikely that they were produced by a metazoan, since the structures change in width along their length, and sometimes merge. More likely, the research suggests, is that these trace fossils were formed by something akin to a slime mold.

The organism was opportunistic, evolving and living thanks to a temporary rise in oxygen levels at the time. When oxygen levels dropped again, and stayed low until roughly 650 million of years ago, the organism probably went extinct. As a result, it’s impact on the evolution of life on earth was probably short-lived.

Read the CBC article here

Get the full scientific article here

By Brittany Laing