Bizarre Fossils Are Neither Plant Nor Animal, But a Weird Fusion of Life

January 21, 2024 8:44 PM

Bizarre Fossils Are Neither Plant Nor Animal, But a Weird Fusion of Life. Euglenids are a group of unicellular eukaryotes that gain energy through both photosynthesis, like a plant, and through consuming other beings, like an animal. These aquatic organisms split off from other eukaryotes roughly a billion years ago, and yet their fossil record for all that time on Earth is scarce. Now, an international team of scientists argues that they have found ancient Euglenid fossils hiding in "an extensive paper trail" of already published scientific research. For years, the shell-like fossils were misidentified as possible worm eggs, algal cysts, or fern spores, partly because of their tiny circular 'ribs' on the inside.
posted by chariot pulled by cassowaries (8 comments total)

In times of stress, these organisms wrap themselves up in a protective cyst, which looks sort of like a three-dimensional thumbprint

This looks a *lot* like a fingerprint. Very cool stuff.
posted by aspersioncast at 9:57 PM on January 21 [1 favorite]

Euglenids were one of the reasons why, in the 1970s, Robert Whittaker & the late, great, Lynn Margulis dumped the Aristotlean idea[l] of {animal vegetable mineral} and proposed a five kingdom classification: plants, animals, fungi, bacteria and "protoctista". The latter (= protists) serving as a grab-bag for all the species, incl Euglena, Amoeba, Paramecium, which a) had nuclei but b) didn't fit any of the other kingdoms. In that same decade, Carl Woese turned all this on it's head when he twigged that some "bacteria" were way off the evolutionary left-field and deserved their own dug-out = Archaea. Last I looked there are three top-level Domains: Eukaryotes, Eubacteria and Archaea with kingdoms below that. But classification is dynamic and there may now be newer better ways of binning the living world as exceptions accrue.
posted by BobTheScientist at 11:56 PM on January 21 [14 favorites]

Also looks like Bavljenac Island in the Adriatic aka Fingerprint Island.
posted by BobTheScientist at 12:05 AM on January 22 [1 favorite]

Oh my goodness this is so cool. I wonder if horizontal gene transfers limit our ability to date/place them using genetic analysis.
posted by neonamber at 12:17 AM on January 22

but no one was able to really put a finger on it.

I see what they did there.
posted by chavenet at 12:33 AM on January 22 [2 favorites]

Euglenids are a group of unicellular eukaryotes that gain energy through both photosynthesis, like a plant, and through consuming other beings, like an animal.

I immediately thought of Venus fly traps and pitcher plants, which use photosynthesis, but eat bugs as well. Not sure if they are related.
posted by tiny frying pan at 6:10 AM on January 22 [1 favorite]

These are supercool fossils! Modernly within Domain Eukarya we recognize a number of different superkingdoms, none of which are the “kingdoms of life” you learned in elementary school. Eugleniids are part of Superkingdom Excavata, along with a number of other organisms, including the intestinal parasite Giardia. For reference, plants are in Archaeplastida along with the red and green algae, and animals and fungi are in Opisthokonta together, along with a bunch of things you’ve never heard of like choanoflagellates.

Many other non-plant/animal/fungus organisms are mixotrophic, and like eugleniids, they all seem to have been heterotrophic organisms who became photosynthetic through secondary endosymbiosis, either gaining a red or green algal cell that became a chloroplast rather than being eaten. This includes dinoflagellates in Superkingdom Chromalveolata and some cool Amoebozoa. Others like diatoms and kelp went through this process but ultimately became primarily photosynthetic and stopped eating other things and now they’re the mist important photosynthesizers on earth.

The non-plant/animal/fungus eukaryotes are fascinating and deserve way more love than they get.
posted by hydropsyche at 6:41 AM on January 22 [7 favorites]

Of course I have heard of the conewhips. Saw one under light microscopy and had the hardest time figuring out what that things was that was pushed instead of pulled by their little whip.

One biologist I asked jokes that maybe amateur microscopy was too exciting for me and I had accidentally contaminated the sample.

Thanks for posting this. Every new discovery that makes the tangled tree of life more complex and interesting makes me happier. And with how cheap and available protein and gene technology is coming, I can only expect more complexity and tangledness to be discovered.

(I am in a one person campaign to translate taxonomical names to local language in fun and memorable ways. Conewhips make me want to go get some dirty water and a microscope, choanoflagellates puts me to sleep.)
posted by Dr. Curare at 8:46 AM on January 24