Remember how I told you most prehistoric sharks we only know from teeth and jaw fragments?
THEN WHAT IN THE NAME OF UNHOLY EVOLUTIONARY DRUNKEN FUCKING IS THIS?
The Helicoprion species (of which there are three proposed, H. bessonowi, H. davisii and H. ergasaminon)…
So when we did the cats I introduced you to the latin binomial (the two names that denote the genus and species of an animal) and how it is usually presented – Capitalised genus (e.g. Helicoprion), lower-cased species (e.g. bessonowi) in italics (e.g. Helicoprion bessonowi). Well here’s a new thing. Once you’ve already named it once in an academic paper, and as long as it won’t cause confusion with other genera, you can abbreviate the genus later on (e.g. H. bessonowi) Yes, you have to learn all this for undergrad biology, yes there are exercises where you will be marked down for getting it wrong, yes I understand the necessity of clear rules of taxonomic designation, yes I still think they’re mostly stupid.
…are known from pretty much one thing and one thing alone – a hellish spiral of teeth, known as a ‘tooth whorl’.
It was a debate between this and the scissor-tooth shark, Edestus sp., as to which I put. The scissor-tooth shark is a nightmare in and of itself. With its bowed, protruding jaws containing saw-blade like rows of sharp, serrated teeth it looks wrong. The thing about Edestus is we kind of actually get why it adapted that way and how it hunted. It is thought it is one of the few known species to ‘slash’ at its prey to injure or incapacitate them. The structures of the upper jaw would indicate some kind of holding and cutting mechanism too. It would basically slash you, saw you and eat you. Cool.
But there’s the rub, for as weird as the scissor-tooth is it doesn’t have an enigmatic spiral of teeth that curls in on itself. Helicoprion does.
There are two reasons I wanted to put this shark in the top ten. One, obviously we’re going to talk about that spiral, but first I want to talk about evolution.
Biologists will tell you that, far from the supposed ‘intelligent’ design posited by theists and those who believe in a universal ‘creator’ – evolution is actually pretty dumb.
Think about it in simple terms and it’s natural trial-and-error. It is making random changes and hoping one of them turns out for the best. There’s a ‘law of large numbers’ aspect to it. This doesn’t just happen with Jane and Dave down the road and their kids. Every single one of the near 8 billion people on this planet has a chance to have a mutation, or have multiple children who have a mutation that goes on to confer a potential advantage, depending on circumstance across all the time life exists.
Some of these advantages will be obvious. One could assume Olympic swimming overlord and consumer of much pot (allegedly) and many cheeseburgers (definitely), Michael Phelps, had there been a sudden flood in the US, may have found himself and his progeny at increased chance of survival due to their ability to swim quickest to the nearest resources and defend them.
Then, through a process of selection for those swimming genes, epigenetics (the environmental changing of activation of genes – Not all genes have to be on all the time) involved the activation of other genes that better suit the aquatic situation of human life, and the fact that Michael Phelps will be one of the few people to be able to get a woman to dry land to make sweet love and impregnate her, suddenly we’ve got more humans with a genetic predetermination for being strong swimmers happening.
As it is, human success is measured in many forms and, mercifully, whilst genetic freaks like Michael Phelps do find themselves successful they are not the only ones. Otherwise, who could beat Michael Phelps? But it is an illustrative example of how a random mutation could, through its own existence, and the right circumstances, become dominant.
That has been happening for somewhere close to 4 billion years, we estimate somewhere around 3.8 billion years as the emergence of life. This has been happening in every organism for that 3.8 billion years.
You can see how a combination of population numbers, and extremes of time, can come up with some wacky shit? Right?
I think it is one of the misunderstandings of evolution that because everything is changing all the time we must be getting new species all the time. No, it’s a slow process and, frankly, without the new to compare to the old, without the speciated-into to compare with the speciated-from it’s a continuum. We would barely notice.
So, to us, we might look at something like Helicoprion and wonder what evolution was ‘thinking’ when it came up with that design but it wasn’t thinking, that’s the point. That spiral is an accident. A continuum of sharks would have had this evolved jaw of ever-rounding, rolling teeth that eventually, for reasons we’d need a time machine to figured out, grew and morphed into the trademarked whorl of Helicoprion and whatever, and however, Helicoprion was eating with that jaw mechanism and was effective enough for it to keep surviving.
If you consider shark tooth dynamics, they continually have new teeth growing behind the old, it sort of makes sense how it could accidently evolve into a spiral if that spiral is found to be effective at something.
I always say, evolution evolves things by accident, but only keeps the things that work (or at least do no harm).
So what’s the deal with Helicoprion? We don’t really know. We assume, at some point, teeth in this arrangement were good for something. Maybe it acted as a good trap for taking big, munching bites out of shoals of small fish, some theorise it may have been good for shredding crustaceans and other seaborne arthropods with hard shells, but I’m not sure we have solid evidence for that, perhaps it’s just a stupid thing evolution did that wasn’t worse than any other shark at the time.
There has been much debate about the placement of the whorl in the mouth of the Helicoprion and for years this placement has been debated, from having it as the upper jaw curling above the head (See Kapinsky’s diagram above) for some reason, to being down the back of the throat.
From what we understand, according to the latest model by Tapanili et. al. 2013 based upon CT scans of a fossil with intact cartilaginous structures (discovered in Idaho, USA in limestone from approximately 270 million years ago) it appears the whorl would have fit, effectively, the entire mouth.
This has led to potential discussion about whether or not it should even count as an Elasmobranch, being placed in the subclass of Euchondrocephali, more closely related to modern day Holocephali, the chimaera, instead. Remember when I mentioned in my Introduction that so many of the taxonomic names to do with sharks are big…Yeah, welcome to marine biology!
What did it eat? Well based upon the whorls we have found, which have been remarkably smooth, without much buffing or scratching from fighting prey, we’d have to assume it was smaller, soft-bodied fish and squid. A 2015 discussion, by Ramsey et. al., proposed a model of the potential movements of the jaw, based upon the 2013 CT scans, indicating a simultaneous bite-shred as it closed its mouth. This would, in effect, create a conveyor belt of death for soft-bodied prey items, moving them down the line of the whorl as the Helicoprion closes its mouth and presses the prey between the whorl and it’s upper palate (the palatoquadrate).
Sorry, I’m trying to keep this sensible and accessible but once you’ve delved deep into the world of over-thinking sharks teeth you have to start using lots of big words! You should have seen the discussion about the various grooves and serrations between Megalodon and the great white that led to Megalodon’s reclassification! It’s basically gibberish to all but the biggest of shark-tooth fanatics.
The point is this thing would open its mouth nice and wide, close it over prey and they would be pushed vertically against the upper-jaw palate, where the positioning and shape of the teeth would push them down the line, shredding them and then presumably be swallowed.
It’s literally a manually operated, built-in, soft-fish and squid shredding circular saw!
Man, ain’t nature remarkable!?
Want to dive deeper into some aquatic shark content?
Our Introduction will give you the basics of shark biology, ecology and natural history.
#10 – The massive, magnificent megalodon – a prehistoric giant!
#9 – The beautiful and quick blue shark
#7 – The frilled shark, a mysterious living fossil with much to tell us about sharks past.
#6 – The Great White, Apex predator, whale scavenger, more intelligent than we thought.
#5 – The Megamouth Shark – One that tells us more about what we don’t know!
#4 – The Graceful Hammerhead family – Much overfished, and is one a veggie?
#3 – The aparently philosophical basking shark! – Happy just existing.
#2 – The longest living vetebrate on earth – The Greenland Shark