It seems that movie franchises often define periods of childhoods, or even entire generations. From Star Wars and Indiana Jones to The Matrix and Lord of the Rings, filmmakers are able to capture the imagination and wonder of millions of people, making them believe, if only for a moment, that nothing is impossible.
For me, the defining movie franchise of youth was Jurassic Park, and I spent months (let’s admit it… years), imagining how much cooler life would be if I knew there was some incredible theme park in the South Pacific where I could go and hang out with some living, breathing dinosaurs.
As I grew up, I accepted the fact that this simply wasn’t going to happen. My science teachers informed me very firmly that once a species was gone, there was no coming back. The word “extinct” had an air of finality that I learned never to question…
I probably should have asked more questions, and believed a bit harder in Steven Spielberg, because as it turns out, my science teachers weren’t telling the whole story.
The Truth Behind the Fiction
While it is unlikely that you’ll ever stumble across a dinosaur while trekking through the jungle, bumping into a species that was previously thought to be extinct is far from impossible. In fact, it has happened nearly 100 times in scientific history, and there are undoubtedly more examples just waiting to be discovered.
A mysterious “comeback” species like this is called a Lazarus taxon, and is basically a species that the fossil record deemed “extinct”, but somehow managed to survive, evading human and scientific detection for decades, centuries, or even entire geologic ages!
A Lazarus taxon refers to the biblical story alleging that Jesus Christ raised a man named Lazarus from the dead, and that name has been associated with miraculous revivals ever since!
There is no magic or religious significance involved in these species “coming back from the dead”; instead, we can blame the imperfection of the fossil record for these amazing natural phenomena.
An Imperfect System
The fossil record has become one of the most important and informative puzzle pieces in the grand picture of global science, and in fact, the oldest fossil that we possess dates back 3.5 billion years (cyanobacteria, to be specific). However, most of our fossils date from the past 500 million years, but in that massive span of time, tens of millions of species have arisen and disappeared.
The fossil record contains all of the creatures (plants, animals, bacteria, fungi etc.) that somehow became trapped in sediment and, over the course of millions of years and intense pressure, became fossilized. When we discover one of these fossils, our picture of evolution and life on this planet becomes a bit more clear. However, the fossil record is far from perfect, because a tiny fraction of creatures ever become fossilized, and an ever smaller fraction are discovered before those fossils are destroyed in some way.
When it comes to Lazarus taxa, those creatures or groups of organisms could have managed to survive in any number of ways. Perhaps following one of the massive extinction events on Earth (Permian-Triassic, Late Devonian, K-T Extinction etc.), when species numbers dropped dramatically, some of these creatures evaded fossilization and survived in small population groups for thousands or millions of years.
These long periods of extreme rarity will probably not show up in the fossil record, so we assume that these creatures were completely wiped out. While many Lazarus taxons are extinct now, appearing in a fossil from 55 million years ago, when researchers thought you went extinct 100 million years ago is still a big deal!
Some other explanations include temporary isolation of species or groups from main sections. For example, let’s imagine that a single species of salamanders lived near a particular river in South America. If a drought struck that area, devastating their entire habitat and leaving nothing living for miles around, we might assume that the species has gone extinct.
However, what if a few salamanders had gotten lost, or poached years earlier, and were being raised in an entirely different habitat 100 miles away? A few generations later, when that tiny population of long-dead salamanders was rediscovered, it would be rather incredible, right?
Although Google Maps makes it seem like the whole world has been explored, there are countless geologic and archaeological sites that researchers have never found, and millions of fossils still buried in the Earth. Our imperfect system of deciding that something is “extinct” is based on observation and deductive reasoning, but there are definitely exciting exceptions.
Lazarus Taxon Celebrities
The most famous Lazarus taxa is definitely the coelacanth, an ancient unattractive fish that scientists had labeled as being extinct for 66 million years, since the same disastrous extinction event that knocked out the last of the dinosaurs. However, in 1938, a specimen of this fish popped up in a fish market in South Africa, ready to eat.
Clearly, it had been hiding away, somewhere in the depths of the ocean, avoiding prying human eyes and fossilization. Some other now-famous examples include the Lord Howe Stick Insect, the Bavarian Pine Vole, the Tammar Wallaby, the Terror Skink of New Caledonia, and the Banggai Crow.
Scientists expect that we will continue to find more of these previously assumed species, particularly with more advanced DNA analysis tech available, and the fact that we know that these incredible creatures do, in fact, exist all over the world.
Lazarus taxa are often confused with other fascinating groups of animals with cool names (zombie taxons, Elvis taxons, and living fossils), but these all describe different groups (zombie – fossils that separate and move through different geologic strata to appear much younger than their extinction; Elvis – mimic organisms that have copied extinct taxons; living fossils – creatures that have essentially stayed the same for millions of years…think cockroaches…).
These rare Lazarus taxa discoveries in the natural world prove that no matter how much scientists think they know, our remarkable planet always has more surprises in store. It is important to remember that our picture of natural history may be impressive, but it is far from complete!
Next time you’re walking through one of the deep, forgotten places of the world, keep your eyes open. You never know what sort of long-forgotten species you may spot… as long as it’s not a dinosaur!