Create a list of articles to read later. You will be able to access your list from any article in Discover.
You don't have any saved articles.
Ancient plant species revealed to be fossilised baby turtles
A case of mistaken fossil identity has been resolved after 20 years.
New research reveals that the plant Sphenophyllum colombianum is actually an ancient fossil turtle, which researchers have nicknamed after the Pokémon Turtwig.
The mystery of a fossil plant’s unusual age has been solved after it was revealed it wasn’t actually a plant at all.
Back in 2003, two five-centimetre-wide fossils covered in leaf-like markings were described as a new species of an ancient group of plants, known as Sphenophyllum. This was quite surprising, as all known members of the group had died out more than 100 million years before the fossil was buried.
To see if the fossils were really plants , a team of researchers re-examined them and discovered that the markings weren’t the veins of leaves after all, but the ribs of tiny turtles.
Dr Edwin-Alberto Cadena, a co-author of the study, says, ‘These are remarkable specimens, not just because of their story, but because they are small hatchlings. It’s really rare to find hatchlings of fossil turtles in general, as the bones in their shells are so thin they can be easily destroyed.’
‘These turtles were likely the relatives of other Cretaceous species that grew to around 4.5 metres long, but we don’t know much about how they grew to such giant sizes. These fossils will help to add to our understanding of that.’
The findings of the study were published in the journal Palaeontologia Electronica.
Though Sphenophyllum colombianum might not be a true plant, other members of the species have been found in many regions of the world. Images © Falconaumanni, licensed under CC BY-SA 3.0 via Wikimedia Commons.
Vegetable, animal or mineral?
For a period of around 110 million years, Sphenophyllum would have been a common sight in wetlands across the world. These plants looked similar to modern horsetails, but died out around 250 million years ago during the Triassic.
This made it quite the surprise when a new species, Sphenophyllum colombianum, was described from Colombian rocks dating to just 120 million years ago during the Early Cretaceous. While it’s not unheard of for some species to cling on long after their relatives have become extinct, it’s very unusual.
To try and resolve the mystery once and for all, the researchers tracked down the original fossils in the collections of National University of Colombia. While they certainly looked leaf-like, a few things didn’t add up.
The shape and margin of the leaf, for instance, didn’t seem to match up with the leaves of other Sphenophyllum fossils, while what had been described as leaf venation looked suspiciously like growth marks in bone.
While the extinct turtle Desmatochelys padillai is found elsewhere in the same rocks, there isn't enough evidence to link the young turtle shells to any species. Images © Sernapi, licensed under CC BY-SA 3.0 via Wikimedia Commons.
When they compared the fossils to museum specimens of living turtles, they were left in no doubt that the fossils were not plants after all. While there’s not enough evidence to assign the fossils to a particular species, the turtle’s botanical origins have been recognised in a new nickname.
Héctor Palma-Castro, a PhD student at the National University of Colombia who led the study, says, ‘Discovering that these plant fossils were actually a baby turtle made me immediately think of Pokémon, where the concept of combining two or more elements together is common.’
‘We nicknamed the fossils after Turtwig, which looks like a baby turtle with a leaf attached to its head. Finding such a fossil was truly surprising and goes to show how your imagination and capacity to be amazed are always being put to the test in palaeontology.’
A closer look at the ‘Turtwigs’ revealed that they were very young at their time of death and were probably less than a year old. Within a few weeks of their death, the turtles would have ended up being buried and started their journey to becoming fossils.
The scientists hope that the reassessment of these plant fossils will inspire more researchers to delve into Colombia’s fossil plant collections, and help to answer some of botany’s larger questions.
Dr Fabiany Herrera, another co-author of the study, says, ‘We may have resolved a small palaeobotanical mystery, but more importantly, this study shows the need to re-study historical collections in Colombia.’
‘The Early Cretaceous is a critical time in land plant evolution, particularly for flowering plants and conifers. Our future job is to discover the forests that grew in this part of the world.’
