The Top 10 Greatest Survivors of Evolution

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When we delve into the history of life on Earth, we uncover the incredible changes that have occurred over millions of years. From single-celled organisms evolving into diverse species like redwood trees, dragonflies, and humans, the evidence of evolutionary change is undeniable. However, amidst this vast transformation, some organisms have remained relatively unchanged from their ancient ancestors. Creatures like sharks, crocodiles, and many others are often considered evolutionary “sluggards” or “living fossils”. But the truth is, these creatures have undergone significant transformations throughout their long existence. They are the last representatives of lineages that were once diverse and varied. While they may appear ancient, these survivors have occupied an evolutionary sweet spot, where their habitats and lifestyles remained stable, requiring little pressure to change. In the words of Charles Darwin, it is the quirks and contingencies of their existence that have allowed these creatures to persist. Let’s explore the top 10 greatest survivors of evolution.

1. Crocodylians

Watch any documentary about crocodiles, and you’re bound to hear the line, “They have gone unchanged since the time of the dinosaurs.” While this statement isn’t entirely accurate, it holds some truth. Crocodylians as we know them today, including alligators, gharials, and crocodiles, have been around for approximately 85 million years. However, they belong to a much larger and more diverse group called crocodylomorpha, which originated over 205 million years ago. These prehistoric crocodylians coexisted with dinosaurs and exhibited a wide range of forms and features. Some were ocean predators, while others were small, land-dwelling carnivores. Modern crocs, though they may appear ancient, are just remnants of an even older and stranger lineage.

2. Velvet worm

Don’t let the name fool you – velvet worms are not worms at all. These invertebrates with stubby legs and smooth bodies are part of a group more closely related to arthropods. Velvet worms have a long evolutionary history that dates back to the Burgess Shale, a 505-million-year-old fossil deposit. While the true affinities of the peculiar creatures found in the Burgess Shale are still debated, one creature named Aysheaia closely resembles modern velvet worms. Although soft-bodied velvet worms don’t fossilize well, you can still find them crawling through the leaf litter of tropical forests today.

3. Cow sharks

Most sharks, from nurse sharks to great whites, have five gill slits on each side. However, there are four species of cow sharks that have six or seven gills – a feature retained from some of the earliest sharks. These deep-water sharks are considered some of the most ancient shark species. Sharks are primarily known for their teeth, and their fossil record is mostly comprised of teeth. The lineage to which today’s six- and seven-gill sharks belong can be traced back at least 175 million years. These opportunistic feeders likely scavenged on the bodies of marine reptiles during the age of dinosaurs, and later shifted to marine mammals.

4. Horsetails

While long-lived animal lineages often steal the spotlight, some plants have also endured throughout history. Horsetails are among these great survivors. These ancient plants can be found growing in patches along stream banks and other wet habitats. What sets horsetails apart is their method of reproduction via spores rather than seeds. Horsetails also have an extensive fossil record, with enormous species once dominating forests before modern trees evolved. In fact, much of the world’s coal originated from ancient horsetails that could reach towering heights of over 100 feet.

5. Lice

Not all great survivors are charismatic creatures. Some of evolution’s success stories come in the form of parasites, such as lice. Feather lice, in particular, have an impressive evolutionary history. Fossil evidence suggests that feather lice split from their hitchhiking relatives between 115 and 130 million years ago. These tiny creatures have adapted to feed on early birds and feathered dinosaurs, remaining remarkably unchanged to this day.

6. Brachiopods

Brachiopods may appear similar to ordinary clams with their two halves, or valves, of a shell. However, these creatures have an unequal size distribution of the valves, earning them the nickname “lamp shells.” While relatively rare today, their fossil record spans an astounding 530 million years. Brachiopods once dominated the seas, with some areas filled with their shells. But their reign ended with the Permian mass extinction, allowing mollusk ancestors to take over. Brachiopods have clung to survival but never regained their former dominance.

7. Ginkgo

Ginkgo trees may not be as archaic as horsetails, but their record of over 175 million years is nothing short of impressive. Today, Ginkgo biloba is the only surviving species, but these trees thrived alongside ferns, cycads, and Jurassic dinosaurs in the past. Modern Ginkgo trees share striking similarities with those that once flourished millions of years ago. Their preference for disturbed habitats, such as alongside streams, may have hindered their ability to compete with other plants. Nevertheless, the fact that Ginkgo biloba survives to this day is truly remarkable.

8. Duck-billed platypus

The duck-billed platypus is a truly odd creature that appears to hail from a different era or even a different planet. This unique mammal with a duck-like snout, beaver-like tail, and egg-laying ability has ancient roots. Monotremes, including the platypus, last shared a common ancestor with marsupials and placental mammals over 175 million years ago. Fossils indicate the presence of platypus-like forms dating back 110 million years. The duck-billed platypus is a true testament to the longevity of this archaic mammalian lineage.

9. Coelacanth

Coelacanths were once thought to be extinct, but a living member of this ancient fish group was discovered in 1938. Coelacanths belong to the “lobe-finned” fish category and are distant relatives of humans. Fossil evidence indicates that coelacanths existed as far back as 400 million years ago, making them the evolutionary cousins of lungfish and our earliest vertebrate ancestors. Today, coelacanths are the last surviving representatives of a once more diverse lineage.

10. Horseshoe crab

The horseshoe crab is the embodiment of a true survivor. With their shield-like carapaces and spined tails, these arthropods look like they belong in prehistoric times. Horseshoe crabs diverged from their arachnid relatives around 480 million years ago, and their basic body plan has remained relatively unchanged. While specific horseshoe crab species have gone extinct, the overall design of these creatures has endured for millions of years. They have witnessed mass extinctions, the rise and fall of the non-avian dinosaurs, and dramatic shifts in climate and geography. Today, horseshoe crabs continue to crawl along the seafloor, a testament to their remarkable resilience.

FAQs

Q: How have these species managed to survive for so long?

A: These species have endured due to various factors such as stable habitats, specialized adaptations, and evolutionary resilience. Their ability to persist in their unique ecological niches has allowed them to weather the tests of time.

Q: Are these species considered living fossils?

A: While some may label them as living fossils, it’s essential to understand that these organisms have undergone evolutionary changes over their long histories. They may retain certain ancient characteristics, but they are not exact replicas of their ancestors.

Q: Are there other examples of great survivors in the animal kingdom?

A: Absolutely! The animal kingdom is full of remarkable species that have defied the odds and survived through the ages. These ten species are just a glimpse into the fascinating world of evolutionary endurance.

Conclusion

The ten species listed above demonstrate the incredible power of adaptation and resilience throughout Earth’s history. These survivors have defied the odds and continue to thrive in the ever-changing world. They serve as a reminder that evolution is a complex and ongoing process, shaping the diverse life forms we see today. As we unravel the mysteries of the past, we gain a deeper appreciation for the remarkable creatures that have stood the test of time.

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