stromatolites – Geobites

August 31, 2022August 31, 2022

The rise of Sponges

Featuring image: Venus flower basket glass sponges (Euplectella aspergillum) in the Gulf of Mexico. NOAA Okeanos Explorer Program – Gulf of Mexico 2012 Expedition, CC-BY-2.0

Paper: Palaeoecological Implications of Lower-Middle Triassic Stromatolites and Microbe-Metazoan Build-Ups in the Germanic Basin: Insights into the Aftermath of the Permian–Triassic Crisis

Authors: Y. Pei, H. Hagdorn, T. Voigt, J.-P. Duda, J. Reitner

The Permian-Triassic crisis was the greatest mass extinction in Earth’s history. But an unlikely animal might have benefited from this cataclysm: the sponge.

Microbial mats like stromatolites represent the lithified remains of different slimy accumulations of microorganisms. While there are many different types, Pei and co-workers investigated a special type of microbial mats with a very different internal structure, called microbial-metazoan build-up, mainly consisting of sponges. By comparing these fossil structures to common stromatolites from the Permian-Triassic boundary, the researcher team could show that sponges profited from the mass extinction with the aid of bacteria.

September 8, 2020September 8, 2020

Did a change in phosphorus cycling lead to the diversification of macroscopic life?

Featured image: The earliest examples of life on Earth are microbial buildups known as stromatolites, like these 1.8 Ga old examples from Great Slave Lake, Canada. What changed on our planet for organisms to evolve from microbes to macroscopic lifeforms?

Paper: Ediacaran reorganization of the marine phosphorus cycle
Authors: Laakso, T.A., Sperling, E.A., Johnston, D.T., and Knoll, A.H.

This is a guest post by Akshay Mehra and Danielle Santiago Ramos. Contact us to submit a guest post of your own!

The history of life on Earth—as recorded in the rock record—stretches back to more than 3.5 billion years ago (Ga). The earliest fossilized remains of living organisms appear in the form of stromatolites, which are laminated constructions built in part (or completely) by microbes. While there have been some tantalizing hints that living organisms were mobile by 2.1 Ga (Albani et al., 2019) and multicellular by 1.6 Ga (Bengston et al. 2017), what is definitively known is that by ~750 million years ago (Ma), complex microscopic lifeforms were widespread on our planet. As time progressed, life became macroscopic. Then, during the Cambrian Era (beginning 539 Ma), most modern phyla (i.e. a grouping of organisms based on body plans) appeared in a flurry of diversification so drastic that it has been nicknamed “the Cambrian explosion.” Scientists are still trying to understand what combination of physical and biological processes may have driven the Cambrian explosion.

April 27, 2020June 10, 2020

Ancient microbes engineered sedimentary deposits

Featured image: Cambrian stromatolites from New York State. Image attribution: James St. John / CC BY 2.0; Wikimedia Commons

Paper: Evidence for microbes in early Neoproterozoic stromatolites

Authors: Zhongwu Lan, Shujing Zhang, Maurice Tucker, Zhensheng Li, Zhuoya Zhao

Stromatolites are ancient, layered deposits of sediments that are characterized by thin, alternating light and dark bands. While microbial fossils have been found in many stromatolites, the biological origin of these structures has been debated. Continue reading “Ancient microbes engineered sedimentary deposits”