I'm afraid the shark is nowhere near the oldest predator, neither is the coelocanth or any other fish.
Consider the horseshoe crab, Limulus polyphemus. They evolved in the Paleozoic, up to 520 million years ago. The species found today have changed little in 350 to 400 million years. Now that's old.
With the sharks, you're talking abouit their evolutionary ancestors dating back up to 400 million years. I'm talking about a species that's older than that.
I knew that biology degree would one day prove useful for something.
All right. First, the discussion was never about the oldest unchanged species but about the oldest predator still alive. And I stressed the
evolution part in Shark's case several times during the discussion.
Second, I don't know where you got your biology degree but you're quite wrong. If we're going to take things litaraly and ignore the part where I said
"...or at least one of the oldest" and that the title is for the most part an
attention grabber, then horseshoe crab ("Limulus polyphemus") is not even close to the oldest predator.
Flatworms ("Platyhelminthes") were the early predators, and already predate the horseshoe crab. They lived
600 million years ago in Proterozioc eon and still exist today.
Cnidaria (jellyfish) were also predators who lived in Proterozoic eon,
600 million years ago. Jellyfish aren't actually a fish but they still predate the horseshoe crab. By the way, the first primitive/prehistoric fish also appeared in Paleozoic era, in Cambrian period, around 520 years ago.
However, the literaly
oldest predators and predatory
species that are virtually unchanged and still alive today are
Myxobacteria. They are
eons (billions of years) old. Now
that's old! And yes, they are defined as predators and actually hunt in packs. They are found in virtualy any environment (soil or water).
Cyanobacteria are actually the oldest species on Earth, unchanged for about 4 billion years but they are not predators.
If you really studied biology, you should've known that predatory bacteria like Myxobacteria are litaraly
the oldest predators and species that are virtually unchanged for eons and still alive on Earth today. Sure, there was other predatory bacteria, even older, now extinct or possibly evolved but their predator-prey relations were different.
Having said that, first sharks still appear in Paleozoic era, which you brought up for the horseshoe crab. The oldest fossils found so far are over 450 million years old. Sharks are
fish. The earliest fish appear in Paleozoic era, which is up to 542 million years old. Sharks usually dwell in
deep waters.
"Deep water fossils are only rarely lifted to levels where paleontologists can recover them, making most deep water taxa disappear from the fossil record."
That is why new evidence is always discovered, and why the extinction or age of certain species is debatable and often proven to be different. It is normal.
In fact, while Coelacanth is said to be the oldest lineage of jawed fish, Sharks are said to have the oldest evolutionary lineage. So, even though the oldest predator and species on Earth still alive are Myxobacteria, it is reasonable and correct to say that Sharks are
the oldest evolutionary-lineage predators on Earth still alive.
Pretty clever, isn't it? Hence, the expression "God's oldest killing machine".
Like I said, don't get too hung up on the title, it's an expression, an attention grabber, and the body of the message always had
"...or at least one of the oldest", which is true and allowed room for debate, taking into account other possibilities that are more literal in their meaning.
Cya!
PS In response to other recent comments. I don't know about actually cheering for any predators. It depends. However, there is always some nut trying to prove that Sharks or Bears are misunderstood, for example, only to get mauled by one during some documentary. Google for "Grizzly Man" to see what I mean.
