Recently, my brother asked me a burning question: If a carnivorous plant ate an animal, would we be able to see that in the fossil record? That question is misleading. He was really asking “If a piranha plant ate Yoshi, would you be able to see it in the fossil record?”
So, let’s break this question down into three parts: did carnivorous plants coexist with dinosaurs, could carnivorous plants grow large enough to eat a dinosaur, and could we recognize this interaction in the fossil record? Here is the quick and messy, Wikipedia driven answer.
Did carnivorous plants coexist with dinosaurs?
That is a complicated question. There are many different types of carnivorous plants (pitfall traps, flypaper traps, snap traps, etc) and they do not constitute a monophyletic group; carnivory has arisen independently multiple times in plants (though some instances of carnivory are due to shared ancestry). To simplify, let’s focus on the species most similar to the piranha plant: the Venus flytrap (Dionaea muscipula).
The Venus flytrap is in the family Droseraceae, which includes 2 species of snap trap plants and the sundew. The fossil record for Droseraceae dates back to the late Cretaceous, which means that there was some overlap between the last non-avian dinosaurs and early Venus flytrap relatives. Yes, carnivorous plants coexisted with dinosaurs.
Could carnivorous plants grow large enough to eat a dinosaur?
Let’s ignore that fact that humans and dinosaurs didn’t coexist (We’re sorry, but the fossils are in another sedimentary layer). To answer this question, we need to make a few assumptions. Firstly, let’s assume that Mario is the height of an average Italian man (just for the sake of the math). That’s about 1.75 m or 5 ft 9 in. Secondly, we want this dinosaur to be some sort of theropod from the late Cretaceous that would be large enough for that average guy to ride. We’ll use Erlikosaurus, a herbivorous theropod, as our Yoshi (T. yoshisaur munchakoopas) stand-in.
So, how big do carnivorous plants grow today? The largest carnivorous plant is Nepenthes rajah, a type of pitcher plant. However, in this respect “large” is a drastic overstatement. The pitcher can only grow up to 41 cm (~16 in) tall and 20 cm (~8 in) wide, meaning that it’s only large enough to trap small animals. No, carnivorous plants couldn’t grow large enough to eat a dinosaur large enough for a person to ride.
Could we see a carnivorous plant eat a dinosaur in the fossil record?
This is the most complicated question. If we assume that carnivorous plants could coexist with dinosaurs and that a snap trap plant could (and did) grow large enough to eat a decently sized theropod, would we recognize what we were seeing? Now, many of the fossil occurrences of Droseraceae come from pollen or seeds rather than leaf impressions. It requires remarkable preservation to preserve a recognizable leaf impression. By itself, fossilization is an uncommon outcome for remains. When comparing the likelihood that a particular structure will fossilize, bone ranks higher than leaves.
This is an oversimplification that ignores many realities of paleontology. Most of what happened in geologic time has not been preserved in the geological record; different environments preserve material better than others and some materials are more easily preserved than others. Many fossils will simply weather away or otherwise never be found. Some will be found by people with little or no interest in fossils or interest only in vertebrate remains. Others will sit in boxes on museum shelves for decades because there is no money to prepare them.
But again, let’s assume perfect conditions. While paleontology is pioneering better 3D imaging and study of fossils, many fossils-particularly plant leaf impressions-are 2 dimensional. Depending on how the fossil is uncovered and who is doing the excavating, it might not be clear what has been preserved. For example, if the fossil was found laying horizontal, the bones might appear to be laying on leaf litter. However, if the fossil had a demonstrably different part and counterpart with bone surrounded by leaf material, high-tech imaging might be able to piece together the story. However, some scientists might see that interpretation as overly fantastical. Paleontologists can be conservative with their interpretations due to the nature of the materials they work with. There is the possibility, though remote, that if the perfect fossil was ever found of a carnivorous plant eating a dinosaur we would be able to recognize it.
The moral of the story is this: any carnivorous plants that did live at the same time as the dinosaurs wouldn’t have been big enough to eat one, but we might be able to recognize it if it did.