My ’22 Top Ten – 11. Crocodile Rock

On December 21st, as I finished compiling Fossiliam’s Top Ten Things of 2022, a thought flickered through my brain. What if something even better happened in the remaining ten days of the year?

My last piece of work was to lead a private hire fossil hunt on the Yorkshire Coast on December 23rd. The only way that was going to end up in the top ten was if we found something truly remarkable, and what were the chances of that?

Ridiculously unlikely, I decided. My expertise is in trace fossils and marine invertebrates. I don’t find – nor even really know how to look for – the sorts of fossils that grab public attention. Earlier in the year I picked up a nodule on Filey beach that I thought was bony, and when I showed it to an expert, they said, “nah, it’s just a network of calcite mineral veins.”

These tiny three-toed dinosaur footprints are as ‘Hollywood’ as my fossil finds usually get.

As I drove across the North York Moors before dawn, a barn owl swept spectrally across the road, and I wondered if this might be the highlight of the day. I was quite, quite wrong.

I met Macy and her dad Randy just after sunrise, about an hour before low tide, and I explained why the combination of glacial erratics and Mesozoic bedrock made fossil hunting on the Yorkshire Coast much easier than the Dorset Coast (every pebble beach on the Yorkshire Coast will yield fossils, but please don’t tell anyone!).

Almost immediately, among the mostly erratic shingle, Macy picked up a large lump of limestone with the edge of a large Dactylioceras ammonite peeking out. Bingo!

A Dactylioceras ammonite found on one of my fossil trips at Cayton Bay.

We soon found Carboniferous corals and gryphites too, and I explained why limestone nodules (or concretions) were the best source of three-dimensionally preserved fossils. I suggested we walk over towards the Jurassic mudstone cliffs now that we were almost at low tide. And as Macy and I closed in on the bedrock, and the possibility of rich pickings, our eyes almost immediately fell upon the same cobble, resting serenely on the beach sand.

It was a pale, slightly greenish-grey nodule, with some very symmetrical, organized-looking dark structures running through it. “That looks interesting,” we said, as we picked it up to examine it. “It looks bony,” we agreed, and turned it over. Looking at the dark parts with a hand lens, they seemed to have the right structure to be bone.

“Vertebrae?” we wondered, but the arrangement and symmetry didn’t look right. The structures seemed to be tapering towards one end, with distinct left-hand and right-hand sides.

“Is it a skull?” we asked, disbelievingly. “Is it a…crocodile skull?”

It reminded me a little of Teleosaurus chapmani in the Whitby Museum, but – as I disclaimed above – I have virtually no knowledge whatsoever of fossil reptiles. I wanted to make no bold promises, and suggested that Macy hang on to it, and see what she could find out later, perhaps when they popped into Whitby.

As heard about on BBC 6 Music, the wonderful fossil crocodile in the Whitby Museum.

We spent the rest of the morning turning up ammonites, and belemnites, and bivalves, and fossil wood, and trace fossils, but nothing was as remarkable as The Skull. I guess it was never likely to be. At the end of the morning, we stopped, and fetched it out again, and Randy gave the cobble a wash, and Macy held it, and I took some photos:

Crocodile rock: top view.
Crocodile rock: bottom view.
Crocodile rock: rear view.

It had to be a skull, didn’t it? And when I showed these photos to a few fossiliferous friends later that day, these were some of the responses:

“Absolutely this is part of a crocodile skull! Heavy pyrite, but what a find! Wish I had found that!”

“That croc block could be a lovely piece – I think I see a scute as well!”

Steneosaur crocodilian – great find!”

We weren’t wrong! Macy and I had found a crocodile rock! Alright, a crocodylomorph rather than a crocodile, but as Melvyn Bragg knows, crocs were more diverse in the Jurassic than they are today. So, what particular kind of crocodylomorph was it?

The Whitby Mudstone Formation has yielded various long-snouted marine crocs, often assigned to the genera Teleosaurus (“perfect lizard”) and Steneosaurus (“narrow lizard”). Comparing Macy’s fossil to the Steneosaurus specimen from Port Mulgrave, described by Gordon Walkden and colleagues in 1987, it looked similar. I might even risk naming some of the skull bones.

I will not, however, risk giving it a generic name: Steneosaurus is a wastebasket taxon, according to Michela Johnson and colleagues. Crocodylomorph is fine. Thalattosuchian is probably fine too. Beyond that, Macy’s Marvellous Mesozoic Marine Monster will have to suffice, until research specialists have been consulted, and expert preparators have removed some of the pyritic limestone.

Whatever happens, Macy has an absolutely lovely fossil: an 180-odd million-year-old croc in a rock. And I have the eleventh-hour extra entry into my ’22 top ten.

All together now…

I remember when crocs were young,
in the early Toarcian.
Rotten silts and stinking bones
turned anoxic muds into fossil-rich stones,
and the greatest kick I ever got
was this thing called the crocodile rock.
While the other kids were shopping round the clock
we were hopping then stopping by a very fine block…

Earth scientist in York, fossilist across Yorkshire. Co-director of the Yorkshire Fossil Festival and palaeontologist for hire. Can be found twittering, facebooking, and instagramming as @fossiliam.

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