New #OA paper in @royalsocietypublishing.org #RSOS: we use CT to describe a 3D shark from the Cretaceous Chalk, giving a rare skeletal perspective on shark evolution. A bit of the backstory in 🧵below featuring 🦴 MYSTERY FOSSILS 🦈 CUTE SHARKS 🦷 CHALK DENTISTRY doi.org/10.1098/rsos... (1/13) - ThreadSky

euphanerops.bsky.social • 18 days ago

New #OA paper in @royalsocietypublishing.org #RSOS: we use CT to describe a 3D shark from the Cretaceous Chalk, giving a rare skeletal perspective on shark evolution.

A bit of the backstory in 🧵below featuring
🦴 MYSTERY FOSSILS
🦈 CUTE SHARKS
🦷 CHALK DENTISTRY

https://doi.org/10.1098/rsos.242011

(1/13)

1 / 2

Comments

euphanerops.bsky.social•18 days ago

This project spun off another project, redescribing extinct Chalk shark Synechodus. This @nhm-london.bsky.social specimen below, was labelled "Synechodus sp.", despite no teeth being visible. Fool that I was, I believed the label and we CT scanned it to find out what Synechodus looked like.

(2/13)

euphanerops.bsky.social•18 days ago

Dear reader, we did not find out what Synechodus looked like, with it swiftly becoming clear this this thing looked nothing like Synechodus. It had a strangely-shaped braincase, the jaws were different and there was no sign of any teeth, Synechodus-like or otherwise. So what was it?

(3/13)

euphanerops.bsky.social•18 days ago

Around this time we found a second Chalk specimen, @nhm-london.bsky.social, this time labelled even less informatively "Chondrichthyes" (i.e. sharks + friends). CT showed this rather unpromising fossil had the same weird braincase, and preserved the whole body back to the pectoral fins.

(4/13)

euphanerops.bsky.social•18 days ago

Skeletal detective work led us to collared carpet sharks (parascylliids): small, beautifully patterned, eel-like sharks from Australia/Indo-Pacific. CSIRO colleagues (inc. co-author Helen O'Neill) helpfully scanned an extant one, confirming these had the same weirdly-shaped braincase.

(5/13)

euphanerops.bsky.social•18 days ago

But what about those missing teeth? After looking more closely at the scan data we realised that teeth were there in both specimens: they were just tiny (1-2mm across) and scattered amongst the very similar-looking dermal denticles in the Chalk matrix (small white things in video below).

(6/13)

euphanerops.bsky.social•18 days ago

Rough models of the teeth and helpful colleagues gave us clues as to what these teeth could be. To be sure though we needed high-resolution data. Incredibly, co-author Kieran Miles was able to extract one specific tooth from each specimen, located in the CT data, allowing us to SEM them

(7/13)

ultraheavybeat.bsky.social•18 days ago

my god the skeleton is so beautiful, like some kind of dark mermaid. great thread btw!

euphanerops.bsky.social•18 days ago

Yeah, a lot easier on the eye than the fossils! Cheers!

Comments

Posting Rules

Reply