The Top 10 Greatest Survivors of Evolution- page 3 | Science | Smithsonian
Current Issue
September 2014  magazine cover
Subscribe

Save 81% off the newsstand price!

Crocodylians are the last living representatives of the crocodylomorpha, an even bigger group that originated over 205 million years ago. (David Ponton / Design Pics / Corbis)

The Top 10 Greatest Survivors of Evolution

Travel back millions of years in your time machine and you’d find some of these species thriving and looking much as they do today

smithsonian.com

(Continued from page 2)

7. Ginkgo

Ginkgo trees aren’t quite as archaic as horsetails, but a record of over 175 million years is nothing to sneeze at. Today these trees are represented only by one species, Ginkgo biloba, but this tree with fan-shaped leaves had its heyday when ferns, cycads and Jurassic dinosaurs dominated the landscape.

Modern Ginkgo trees are not very different from those that herbivorous dinosaurs may have fed on. A recent Paleobiology study by Wesleyan University paleobotanist Dana Royer and colleagues found that Ginkgo trees seem to do best in disturbed habitats alongside streams and levees, a habitat preference that may have been their downfall. Scientists know from living Ginkgo trees that they grow slowly, start reproducing late and are generally reproductive slowpokes when compared to more recently evolved lineages of plants that live in the same places. Ginkgo trees may have simply been out-bred by other plants when suitable habitats opened up, but this makes it all the more remarkable that one species managed to survive to the present day.

8. Duck-billed platypus

The duck-billed platypus truly looks as if it belongs to another era, if not another planet. In fact, when 19th-century European naturalists first saw stuffed specimens sent from Australia, some scholars thought the animals must be a joke. But evolution wasn’t kidding—here was a mammal with a duck-like snout and a tail like a beaver and that laid eggs.

Monotremes, like the platypus, are strange mammals. These archaic, egg-laying forms last shared a common ancestor with marsupial and placental mammals over 175 million years ago, and rare fossils from Australia indicate that there have been platypus-like forms since 110 million years ago. Though often reconstructed with a narrower-snout, the Late Cretaceous Steropodon was a close cousin of early platypuses. A much closer relative to the modern platypus, known as Obdurodon, has been found in more recent rocks spanning about 25 to 5 million years ago. This animal is different from its living relative in retaining adult teeth and some particular skull characteristics, but the skull shape is strikingly similar. Rather than being a new kind of creature that evolved after the dinosaurs, the duck-billed platypus is truly a more archaic kind of mammal with roots that go far deeper than most other mammals on the planet.

9. Coelacanth

Coelacanths were supposed to be dead. As far as early 20th-century paleontologists knew, these distant fishy cousins of ours—categorized as “lobe-finned” fish because of their fat fins supported by a series of bones similar to those in our own limbs—had gone extinct by the end of the Cretaceous, about 66 million years ago, along with the mosasaurs, pterosaurs, ammonites and non-avian dinosaurs. But it in 1938 Marjorie Courtenay-Latimer, a curator at South Africa’s East London Museum, recognized a very strange fish lying on a dock after getting a tip about something strange from the deep. As it would turn out, the fish was a living coelacanth—she might as well have found a living Tyrannosaurus.

Paleontologists have discovered fossil coelacanths younger than 65 million years old since 1938, but, since these were unknown when the fish was re-discovered off South Africa, the discovery of a living member of the group immediately catapulted the fish to fame. Two species have since been recognized, and they are different than their prehistoric relatives—enough to belong to a different genus, Latimeria—but they are still quite similar to their prehistoric cousins. Creatures recognizable as coelacanths go back to about 400 million years ago, and these fleshy-finned fish were the evolutionary cousins of lungfish and our own archaic forerunners—the very first vertebrates to walk on land were specialized lobe-finned fish related to the recently discovered Tiktaalik. Like many other organisms on this list, though, living coelacanths are the last of a once more widespread and varied lineage.

10. Horseshoe crab

Tags
About Brian Switek
Brian Switek

Brian Switek is a freelance science writer specializing in evolution, paleontology, and natural history. He writes regularly for National Geographic's Phenomena blog as Laelaps.

Read more from this author |

Comment on this Story

comments powered by Disqus