Are sharks older than trees? Both sharks and trees have been around for millions of years, but it might surprise you to know that sharks are even older than our forest friends.
Fossil evidence shows that the earliest sharks evolved in the Late Ordovician period, around 450 million years ago.
By comparison, trees are relatively new to Earth, appearing just 360 million years ago in the Devonian period. Humans don’t even enter the equation – we’ve only been here for about 300,000 years!
If anything holds the secret to survival, it must be the shark.
By exploring the shark’s prehistoric roots and subsequent evolution, we might find out what that secret is and whether it will be enough for sharks to survive the next mass extinction.
Although sharks have changed over the years, adapting to different climates, meteorological events, and varying food sources, they still have many features that existed some 150 million years ago.
There are even a few primitive shark species that exist today in much the same form as they adopted some 300 million years ago.
How Long Have Sharks Been Around On Earth?
Fossil evidence proves that sharks existed before trees. Ancient sharks are markedly different from many of the sharks we know today, but still share certain familial features.
Some shark species have survived relatively unchanged. The frilled shark, for instance, is what’s known as a living fossil because it’s adapted so little over.
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Its ancestors were around during the carboniferous period in the latter part of the Paleozoic era, but there’s little difference between them and today’s frilled shark.
Somehow, this species discovered its secret to survival early on and decided to skip about 300 million years of potential evolution!
Other primitive species include the Greenland and Nurse sharks, but they even bear little resemblance to the first shark on Earth.
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What was the First Shark on Earth?
Experts believe the earliest sharks descended from a “small leaf-shaped fish that had no eyes, fins or bones.”
These fish were the predecessors of both bony and cartilaginous fish, of which sharks belong to the second family.
The first recognizable shark species was the Cladoselache. Like many other early sharks, their mouths were located at the front of their snout – a trait that the Megamouth Shark, Frilled Shark, Angelshark, and devil rays still have today.
The first “true shark” species arrived in the ocean precisely as the first tree sank its roots into the Earth. 380 million years ago, a species known as the Caldoselache was speeding through the ocean in pursuit of small fish and shrimp.
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While most modern-day sharks have five gills, a few surviving species, including the Broadnose Seven-gill shark, still have seven, as did the Cladoselache.
In addition to losing some gills along the way, some other traits have disappeared over time.
The Cladoselache had a thin, fragile skin which was soon replaced with “denticle armor plates” that scientists suggest protect the shark against “predators and ectoparasites, reduce mechanical abrasion and possibly minimize swimming-induced drag.”
What Was the First Tree?
The world’s first tree was the now-extinct Archaeopteris. It emerged 370 million years ago and had the same branched trunks, buds, and reinforced branch joints as many of today’s trees.
The Archaeopteris was the first species to establish an extensive root system and, in doing so, changed the world it inhabited much more than the emergence of the first shark.
Stephen Scheckler, a biology and geological sciences professor at Virginia Polytechnic Institute, says the roots of the Archaeopteris “had a profound impact on soil chemistry,” changing the Earth’s ecosystems forever.
They also impacted the shark.
Long before the first trees emerged, the only plants on Earth were primitive mosses and algae. While they may sound innocuous, some believe these first simple plants “triggered both an ice age and a mass extinction of ocean life.”
Plants and trees were also responsible for the second mass extinction, which would have impacted the shark, even though it survived the experience.
Research indicates that a mass extinction event that occurred 66 million years ago caused sharks to shrink in size and change their diets.
By comparing the fossils of the oldest shark teeth with later findings, paleontologists at the Natural History Museum in London have discovered that large predators, like the Megalodon, disappeared after the extinction, along with the dinosaurs.
Smaller shark species dominated the warmer oceans of the post-extinction period, feeding on small fish and squid, just as many of today’s shark species do.
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How did Sharks Survive Five Mass Extinctions?
Periods of environmental upheaval have forced sharks to alter their diets, get smaller, grow larger, move into different habitats, and even share the water with humans. As they’ve adapted, they’ve also developed certain traits that have made them the efficient survivors we know today.
Researchers in Sweden believe sharks’ secret to survival comes from their ability to repair DNA.
This trait has long been thought to make them impervious to human illnesses like cancer. Sharks also have an astonishing ability to heal, and scientists believe that shark DNA could hold the key to improved wound healing and blood clotting in humans.
To get a better idea of how sharks evolved, we’re going to focus on two of the most iconic species – the great white and the hammerhead.
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The Evolution of the Great White
There is nothing straightforward about the Great White’s evolution, and few scientists seem to agree on how this powerful predator came into existence.
Some argue that the Great White descended from the monstrous Megalodon others that it’s closely related to the Mako shark, which has been around for about 60 million years.
Fossil evidence suggests that the first Great White appeared sometime during the Miocene Epoch, making this shark species around 20 to 30 million years old.
The two main trains of thought maintain that the Great White either evolved alongside other megatooth species like the Megalodon or that it branched off from the early Mako shark.
Again, it all boils down to the teeth. Some researchers emphasize the similar “saw-like edges” found on the teeth of both the Megalodon and the Great White.
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Others, like Chuck Ciampaglio, an assistant professor of geology at the Wright State University Lake Campus, argue that the tooth growth trajectories and serration densities of the Great White are more in line with those found in the Mako than the ancient megatooth.
Some shark experts, including David Ward a research associate at the Natural History Museum, believe this later theory is so widely accepted that “fewer people believe the big megatooth sharks are related to the great white sharks than believe the Earth is flat.”
The Evolution of the Hammerhead
Back in the golden age of sharks, strange adaptations and additions were all the rage.
Around 290 million years ago, creatures like Helicoprion patrolled our seas. That shark species featured a buzz-saw-style teeth arrangement on its bottom jaw. Other weird and wonderful developments included the Dunkleosteus with its bladed teeth.
However, the first shark to feature a hammer-shaped head is only thought to have appeared about 20 million years ago. All types of modern-day hammerheads evolved from that one species, including the diminutive bonnethead, the curious Winghead, and the distinctive Scalloped hammerhead.
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A study conducted in 2010 traced the DNA of hammerhead sharks back “millions of generations” and discovered that the hammerhead’s signature cephalofoils, or wide, flattened heads, “underwent divergent evolution in different lineages over time.”
Professor Andrew Martin of the ecology and evolutionary biology department at the University of Colorado believes this was largely “due to selective environmental pressures.”
The bonnethead’s much smaller cephalofoil, Martin believes, is indicative of a species that sacrificed “locomotion advantages for prey detection and visualization.”
The cephalofoils of the larger hammerheads “appear to provide ‘lift’” much like an airplane’s wings, making their hefty bodies more buoyant and easier to maneuver.
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FAQ
Did Sharks Exist Before Trees?
The first ancestors of today’s trees, the Archaeopteris, appeared about 385 million years ago. The first “true” shark species, the Caldoselache, emerged at much the same time.
If we go back even further, we find more primitive tree species, like the cladoxylopsids, which “dominated Earth during the Devonian period from 419 million to 358 million years ago.”
Sharks were also around over 400 million years ago but, like the first trees, show little resemblance to modern-day species. The first trees had hollow trunks, while the first sharks may have been without teeth.
Whether trees or sharks came first is a difficult call to make, but one thing we can be sure of, the existence of trees influenced the subsequent evolution of the shark.
The mass extinction event that took place 66 million years ago is widely held responsible for shrinking sharks. The huge megatooth sharks started to die off, leaving their smaller cousins to take over the seas.
Now, our modern-day species faces another mass extinction in which it’s not their size that’s endangered but their population. There is only one species responsible for this decline: humans.
How Old are Sharks as a Species?
Sharks are around 450 million years old. The oldest fossil evidence dates back to the Late Ordovician period but, so far, only “shark-like scales” have been found. The lack of any shark tooth fossils suggests to some that these early predators may not have been “true sharks.”
The earliest shark teeth ever found date back 420 million years to the Early Devonian period.
Named Doliodus problematicus, this early shark ancestor has been described as the “least shark-like shark” and is, according to some, more of a bony fish “with a shark’s head, pectoral skeleton, and teeth” than a true shark.
If that’s the case, then the first shark species is the Caldoselache which isn’t much older than the oldest tree.
Are Sharks Older than Dinosaurs?
Dinosaurs appeared on Earth around 230 million years ago and vanished about 165 million years later.
Sharks, on the other hand, appeared some 450 million years ago and are still around today. This is proof of the shark’s evolutionary superiority and ability to adapt to climatic changes by changing its habitat and diet.
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According to Emma Bernard, a curator of fossil fish at the Natural History Museum, generalism is the key to the shark’s survival because “the more generalist an animal is the more likely it will be to adapt and survive changes in its environment, and the group as a whole will survive.”
Conclusion
Compared to the oldest living species on Earth, sharks are surprisingly young. Evidence suggests that some jellyfish species have been around for nearly 600 million years, making them considerably older than the shark.
Sharks did emerge before the first trees appeared on Earth, but they bore little relation to the sharks we know today.
Some shark species have remained relatively unchanged during millions of years of evolution, whereas others have been forced to change and adapt to different climates and conditions.
Even today, sharks continue to evolve. Just before writing this, the first Great White was spotted off the UK coast, suggesting a shift in its climatic preferences.
However, whether the modern-day shark can adapt enough to survive our human onslaught remains to be seen, and scientists fear that the current sixth mass extinction could mark the end of many of the shark species found on Earth today.
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Nicky is a British adventurer and animal lover who spends her time exploring the natural world and writing about her experiences. Whether on horseback, underwater, running, hiking or just standing with a fishing rod in hand, she embraces everything her adopted home of South Africa has to offer.