Duncan McIlroy

Introducing the soft-bodied fossil Paleocanna tentaculum n. gen. n. sp., a tube-dwelling medusozoan. The first 3 authors are students.👏

www.cambridge.org/core/journal...

broad Charnia frond at the bottom with a narrow frond right at its tip lying in the same orientation

This #FossilFriday is brought to you from the #Ediacaran of #InnerMeadow with the observation that #Charnia brasieri sometimes have #Trepassia like little feathers on top of their fronds. Part of a review paper coming out next week on life attitude of rangeomorphs :-).

bedding surface with large hemispherical Nimbia and several varieties of the chambered Palaeopascichnus gracilis and narrow P. linearis

detail showing the narrow chambered palaeopascichnus linear is

large Aspidella terranovica (oval) much smaller three lobed triforillonia beneath and a variety of chambered protists Palaeopascichnus

It’s midterms here at MUN & with cleanup from a 75cm 2 day snowstorm too it’s been a disrupted week, so a quick #FossilFriday post- #KotlinCrisis bedding plane from Ferryland NL with #Palaeopascichnus, #Aspidella terranovica & #Triforillonia material of Dr Latha Menon (submitting next week!!)

Well said.
Good science stimulates more science :-)

Here’s a link to a 15 min interview i did last week about #Aninoides and a link to the great comets of 1811 and 1819 via the Beothuk woman #Demasduit if you are interested :-)

www.cbc.ca/listen/live-...

kwnsfk27.r.eu-west-1.awstrack.me/L0/https:%2F...

A great first collaboration with Jeff Peakall @hyperpycnal.bsky.social
whose work anyone looking at enigmatic bedding plane structures would be well advised to look up :-)

Comparison of the frondose features in the Dongpo Formation with uninterrupted chevron marks (A−D) and the Ediacaran Charnia for comparison (E). (A) Uninterrupted chevron marks from the Carboniferous Gull Island Formation, Ireland (modified from Doyle and Hoey, 2022); (B) and (D) frondose forms from the Dongpo Formation (modified from Wang et al., 2026); (C) uninterrupted chevron marks from the Lower Silurian Aberystwyth Grits, Wales (modified from Dżułyński and Walton, 1965); (E) Charnia ewinoni from the Ediacaran of Newfoundland (modified from Pasinetti et al., 2025). All scale bars are 1 cm. Portions of the branch-like structures highlighted in (B-D), primary branches in (E) are offset not opposite and have second (red) and third order branches (green) highlighted as is typical of Ediacaran rangeomorphs.

Earlier this year there was an article on the beautiful new #Ediacaran #Dongpo Biota in China, it has some lovely fossils in it. Well worth a look!
There were also some things interpreted as fronds that we consider to be abiogenic uninterrupted Chevron marks. doi.org/10.1016/j.pr...

unnamed elongate Arboreomorph frond with broad flat disc numerous small branches arise from a central axis at a high angle

reconstruction of an elongated frondose arboreomorph organism with an inferred upright mode of life. Depicted on a hypothetical deep marine seafloor with patchy white microbial communities

coming soon another new Ediacaran taxon from Newfoundland. This one is an #Arboreomorph from the #Ediacaran of the NE Avalon Peninsula discovered and written up with PhD students Pascal Olschewski @simonrosse.bsky.social. The art needs some work to do justice to the fossil but Happy #FossilFriday!

I can only imagine, it is truly dreadful.

a lobster’s eye view :-). Very fun

It is interesting to note Retallack’s name in the podcast but if is conduct in person is anything like how he publishes his doctrines then i’m not surprised.

The Epstein Files and Paleontology | Weird and Dead Podcast Get more from Weird and Dead Podcast on Patreon

From @geopetalfabric.bsky.social and @maryanningsrevenge.bsky.social.

You can follow the podcast at @weirdanddead.bsky.social.

www.patreon.com/posts/150459...

Agreed. The diversity of the pre Kotlin Crisis interval is so low and the rate of background extinction is basically nonexistent meaning it’s very difficult to compare to the Phanerozoic mass extinctions. Which is why we stopped short of claiming it as such.

Yes we lost the Trilobozoa like tribrachidium (sadly) but also a lot of the frondose genera Rangeomorpha and Arboreomorpha).
We just (last week) extended the range of many taxa from 563 to 560Ma which makes the Kotlin Crisis much more profound. i can send you a pdf if you email or researchgate.

Martin Brasier recognized the event in Avalonia and Baltica (in high latitudes) and called it the Kotlin Crisis and subsequent “Kotlinian Dead Zone” in 1996.
Before it we have the beautiful Rangeomorpha, afterwards just lots of little discs and giant protists.

About 11 million years before the end Ediacaran extinction event and the start of the Cambrian radiation of animals, the earliest animal faunas experienced their first extinction at 550 million years ago. We lost a lot of the stranger Ediacarans then but the animal ancestors made it through.

ovoid Aspidella terranovica with central groove next to 3 lobed Triforillonia

Chambered branching protistan fossil Palaeopascichnus left and a bulbous, discoidal Nemiana sp bottom

This #FossilFriday, how about a little look forward in the #Ediacaran to the post Kotlin Crisis extinction event strata in in Newfoundland. doi.org/10.1130/G542...

The post-extinction biotas are dominated by discs such as #Aspidella terranovica and the giant protistan #Palaeopascichnus.

TLDR; it is too early to stop doing taxonomic & natural history work and exclusively do meta-analysis; our existing datasets are highly structured & biology is weird. we shouldn't assume we already know enough to extrapolate a species' needs for conservation- we still need taxonomy & autecology

thank you :-) it’s hard to imagine the how hard lives of those captive women were.

We love being able to colour in some of the details of their day to day lives.

Thank you Julia :-)

Digging up history What do a fossil, a comet and Beothuk history have in common?

Here is a writeup of our work on #Aninoides and how it helped us to uncover a little bit of Beothuk astronomy. Obviously :-)

With huge thanks to @julialaite.bsky.social

gazette.mun.ca/research/dig...

So it seems that the Kotlin Crisis and subsequent Kotlinian Dead Zone recognized by Brasier are coincident with a major turnover of the Ediacaran biotas. The first major #Extinction that the #Eumetazoa ever experienced!

doi.org/10.1130/G542... for those with access, or drop us an email.

This is a bush like Primocandelabrum, perhaps the best one in Newfoundland, it has a big disc and poorly preserved stem. Under study by MSc student Helena Muirhead-Hunt at the moment

2) That extinction is much more profound than previously thought and 3) the partitioning of the white Sea and Avalon Assemblages seem to be mainly ecological/palaeo environmental as other authors have suggested. Not chronologically separated as many have implied.🧵

Charniodiscus procerus with a long stem, large disc, and a frond that has the typical U shaped branches that cross a central axis

Inner meadow site yielded a date of 550.78+-0.6Ma. That is as young as the youngest White Sea and Australian assemblages!
We now have evidence that 1) the extinction event at 550Ma that Martin Brasier dubbed the Kotlin Crisis in 1996 included extinction of the Avalon Assemblage taxa too.🧵

red is the Avalon assemblage the chart shows diversity (dark prior to this paper and lighter including our data. note that it ranges to the end of the dark blue White Sea Assemblage and many of those taxa go extinct at the junction with the Nama Assemblage at 550Ma

The Avalon Assemblage has not been a big part of that story. The weird and wonderful #Rangeomorpha and #Arboreomorpha of Avalonia were thought to have gone extinct at 560 Ma ish so not part of the main narrative…
But as of today that narrative is no longer true! 🧵

a fan shaped fossil of Plumeropriscum centre, not the best specimen known but it has the fractal branching in the crown typical of the genus Dark areas are glacially polished.

We have been using 3 Ediacaran assemblages, The deep marine Avalon (575-560 Ma ish) the shallow marine White Sea (560-550 Ma) followed by an extinction event after which we see the depauperate Nama Assemblage which ranges from 550-538Ma. Which is where the Ediacaran biota as a whole went extinct.🧵

A lovely little Trepassia like a long narrow leaf with fractal-like branches

We now have the site excavated from
beneath the field to about 20x20m and we have not found the edge yet! Our rate of new discoveries has slowed as we have found most of the Avalon Assemblage taxa at the site. The genus level diversity count is at 19 (that is just the taxa we can put names on). 🧵

leaf shaped fossils of Charnia brasieri and Trepassia sp.

Mike Simon and Pascal removing the overlying soil (all by hand) the area in front is the size of the site in May 2025

Happy #FossilFriday how does a thread about the Inner Meadow biota and unexpected age for the fossils, and a refocusing of Martin Brasier’s #KotlinCrisis sound?
We’ve been trickling out our findings from Inner Meadow including #Charnia brasieri, #Aninoides and there's even cooler stuff in review. 🧵