Podcast 344 - Time to Sponge
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The gang discusses two papers that look into evidence of early innovations in sponge evolution. The first paper uses geochemical data to estimate the origin time of demosponges in the fossil record, and the second paper uses phylogenetic methods to map out spicule evolution in the history of sponges. Meanwhile, Amanda has good harvest, James catastrophizes, and Curt stirs the pot.
Up-Goer Five (Curt Edition):
The friends look at two papers that look at a group of animals that pull in water inside them and people use their bodies to clean themselves and other things. These things have a lot of soft parts and the hard parts they do have were probably not around when this group first appeared. So the first paper is looking for changes in rocks that could be because these animals were around. Some of the changes have been shown could be caused by other kinds of living things that are not this group of animals, so the people on this paper did a lot of work using different things today to see if they could make stuff that could be found in rocks. They say that the stuff they have in rocks is coming from these animals and not the other things because of what they looked at.
The second paper looks at how these groups of animals that pull in water are grouped together and uses that to see when they first appeared and also when they started making hard parts. They do not use the first paper in how they try to see when these animals first appeared. They show that the hard parts appeared a lot of times in the history of this animal group, and that main groups of these animals may have gotten their hard parts on their own, maybe many times.
References:
Shawar, Lubna, et al. "Chemical characterization of C31 sterols from sponges and Neoproterozoic fossil sterane counterparts." Proceedings of the National Academy of Sciences 122.41 (2025): e2503009122.
Rossi, Maria Eleonora, et al. "Independent origins of spicules reconcile paleontological and molecular evidence of sponge evolutionary history." Science advances 12.2 (2026): eadx1754.
