The evolution of turtles is remarkably straight-forward. The ancestors of our modern-day turtles split off from other reptiles sometime around the Permian period. These reptiles had elongated ribs that spread over the body, offering some protection against predators. Over time, these ribs fused together to create the turtle’s iconic shell. Fossil evidence shows that the basic shape of the turtle was pretty much established by the Jurassic, and would change very little between then and now.
Terrapene fungus agrestis
The oldest species of turtle found in the Mushroom Kingdom are the squat, quadruped variety found in the first and third Super Mario Bros games. Their domed shell with its hinged bottom clearly designates them as members of the genus terrapene, better known to us Americans as box tortoises, in the family Emydidae. Despite being much larger, they are very similar to common box tortoises in behavior and ecology. They are not terribly fast, aggressive or emotive and will retreat into their shell when threatened. They are responsible for occasional Mario deaths, but usually as the result of poor gameplay by Mario as opposed to active hunting. Most likely they are simple vegetarians.
There are two varieties of the original koopa troopa, the red-shelled and the green-shelled. While they have different coloration and have adapted seperate behavior, there is not enough genetic evidence to determine if they are seperate species. For simplicities sake, we will call this four-legged troopa Terrapene fungus after its country of origin, and describe its two subspecies as Terrapene fungus agrestis (green troopa) and Terrapene fungus montanus (red troopa). Like their North American cousins, these turtles have changed very little since prehistoric times, but at some point in the history of the Mushroom Kingdom, a fascinating evolutionary change took place.
Oesovariabilis erectus, the earliest tool-using turtle
From the very first Super Mario Bros, we see evidence of turtles that not only walk upright, but also who use tools, build and live in brick castles, and have fully opposable thumbs. There is clearly enough genetic variation to place these koops into their own new genus, Oesovariabillis, which includes hammer bros, boomerang bros, magikoopas and their ilk. But how did this transformation take place? There is no record of any kind of “Terrepene erectus”, so presumably the “missing link” between Terrepenne and Oesovariabillis is long extinct.
Some of you may wish to point to the “koopa troopas” that first appear in Super Mario World as this missing link. After all, they have the same basic shape as Terrepene fungus except that they walk upright and have developed hands. At first glance, it would be simple to say that there was a direct genetic ascent from Mario Bros troopa to Mario World troopa to hammer bros. However, the troopas of Super Mario World have evolved another feature that shows they are actually descended from the more fearsome hammer bros, rather than the other way around. To see what this is, we must examine the variations in troopa behavior in response to attack.
A Pseudeskelone peripatea escaping from a predator
When a Mario jumps atop a Terrapene fungus, the turtle immediately retreates into its shell. The tool-wielding members of Oesovariabillis traded some of their shell’s defensive strength for the greater mobility and adaptability that walking upright grants. They can no longer retreat into their shells, and quickly die when jumped upon. In exchange for this weakness, they have gained the ability to develop and wield fearsome weapons. The best defense can be good offense, after all. When a Super Mario World troopa is jumped on, it quickly flees its shell and retreats as best it can. In many cases, the Mario simply moves on and the shell-less troopa escapes with its life. But how can this be? Since turtle shells are connected directly to the ribcage, it should be impossible for a turtle to “flee” its own shell without killing themselves.
The simplest explanation is that the shell these koopas wear is not their own. As Oesovariabillis continued to evolve, their shells became smaller and smaller, granting them more flexibility both physically and environmentally. However, it also left them without even the most basic of defenses. Members of this new genus, Pseudeskelone, had to come up with a cultural answer to this problem. They would “borrow” and use the shells of other animals. As this cultural mechanism proved useful, it began selecting for turtles with smaller or more flexible natural shells who could better worm their way inside discarded shells of Terrapene fungus. The modern day troopa, Pseudeskelone peripatea, has almost no visible shell at all and can thus easily fit into any shell it stumbles upon. We do not know enough about koopa culture to know ifperipatea scavenges the shells of dead turtles like a hermit crab, or if they hunt or even domesticate their less developed ancestors for their shells. However, in the Paper Mario series we have seen many successful communities of Pseudeskelone peripatea living together. Hominid cultural development was increased by humans domesticating and co-evolving with many species of plants and animals. While we have not seen any herds of “lesser” troopas being harvested for their shells, Pseudeskelone communities bear the hallmark of a culture with a history of agriculture and domestication.
The evolution of Koopa skeletons
So if the Super Mario World troopa is not the missing link between Mario Bros troopas and hammer bros, how did this transformation take place? Without a more thorough fossil record we cannot definitely answer this question, but we can make educated guesses based on the environment both species are found in. Terrapene troopas are nomadic in nature, constantly on the move so as not to overgraze an area. “World” 1 of The Mushroom Kingdom is a country with many hills and valleys. Sometimes hills jut up seemingly at random and create intricate “platforms” the local wildlife must traverse. We also know that the neighboring “World 2” is a desert and that “World 3” is a large, marshy sea. Long ago, the sea probably stretched across all three Worlds. The extreme appearance of the hills and valleys indicates that the region once had very chaotic volcanic activity. At any given year an earthquake might drive up a huge wall of earth that would redirect water and flood an area. As the nomadic koopas had to cross these flooded plains in order to reach food, those that could hold their heads above water would be more likely to survive and mate. Remember that box tortoises, unlike freshwater or sea turtles, are not aquatic at all and cannot swim. Over time, koopas appeared that could raise themselves up on their back legs for a short period of time in order to cross the flooded plains. We see this behavior with some nomadic apes in Africa. While they prefer to walk on all fours, when they are forced to cross a marsh they will rise up and wade through the water on two legs like a human would. Koopas that could stay on their back legs longer would be more likely to survive long trips and would also be more likely to discover new uses for their hands. This in turn would select for koopas with more dexterious digits and minds more suited for tool-use. Eventually the volcanoes under the kingdom became dormant and the worlds settled into their current static forms, but the newly upright turtles found their gifts were still useful.
But turtles with tools are not the wildest new form of chelonian to evolve in the Mushroom Kingdom. Tune in next time for an in-depth look at the even more bizarre descendants of the humble troopa.