A New Palaeontology Puzzle for UNE Discovery

By Dr Kieran Meaney, UNE Discovery 

Palaeontology is a science plagued by an incomplete record. Most fossils only preserve “hard” parts such as shells, teeth, and most notably, bones. It is very rare to find fossils with skin or muscle preserved, for example. When we think of fossils, often what comes to mind are huge dinosaur skeletons; complete, intact, and on display in museums. No skin, muscle, or internal organs to be seen, just bones. But even an intact or complete skeleton is rare to find.

In order for something to become fossilised, it must be buried very quickly after it dies. If it isn’t, scavengers will eat all of the meat off of a dead animal, and the bones get broken up and scattered. Even if a scavenger didn’t disrupt the carcass, soft tissues will start to rot away in a matter of days. Quick – ideally immediate – burial is required for good fossil preservation, and we rarely get so lucky.

This brings us to the palaeontology research that inspired UNE Discovery’s new update to our very popular Palaeontology Puzzles activity. In the past, this activity involved reconstructing a rabbit skeleton and trying to determine what the “mystery” animal was based on the bones. Since soft parts like the long ears and fluffy tail don’t get preserved, this made the task a very interesting challenge. However, we had the benefit of having modern rabbits to compare the skeleton to. But what if we didn’t?

The further we go back into the past, the more different life becomes to what we see alive today. In the last 65 million years, we get many mammal fossils of species somewhat similar to those alive today. In the Mesozoic, we find an abundance of dinosaur fossils. Going further back into the Palaeozoic, we find strange giant amphibians and creatures sharing reptilian and mammalian traits. Eventually, we find ourselves in the Cambrian, approximately half a billion years ago. During this time, multicellular life was still quite a recent development, and the life forms we find from this time appear very alien. The spiny worm Hallucigenia, or the trunked and 5 eyed Opabinia are great examples of this.

Hallucigenia reconstruction

Opabinia reconstruction

When looking at fossils from this time, if the animal is not preserved intact, we might not have a good reference for what the living thing actually looked like. A creature covered in scales, armoured plates, or spines might have simply fallen apart after it died leaving a bizarre jigsaw puzzle for modern palaeontologists. Such is the case of Dailyatia.

Dailyatia is a group of species known only from their sclerites. These are small shell-like structures which grew from the soft body of the animal, possibly forming a segmented armour over the creature. I say possibly, because all we have are the separated sclerites of the creature. These sclerites are tiny, often found in the size range of 2-5mm. Dailyatiasclerites typically fall into three distinct groups, referred to as A, B, and C sclerites, with some sub-categories in each.

Sclerites

A’s are axially symmetrical; if you cut them down the middle they would be mirror images of each other. B’s and C’s show left and right versions, like your own hands or feet. Because of these characteristics, reconstructions of this animal place the A’s along the centre of the body like a spine, with B’s and C’s on either side. The ratio of each type of sclerite is also important. B’s make up fewer than 10% of the total sclerites found, suggesting they grow on an extremity such as the head of the animal. Think about your own skeleton. You only have one skull, but many vertebrae and ribs. The A’s make up approximately 30% while the C’s make up the remaining 60% of the sclerites. This fact, along with the left and right versions of the C’s, has been interpreted to mean that the C sclerites flank the A’s along the length of the animal, with the B’s growing on the head to allow for a different range of motion.

Dailyatia reconstruction M. Betts, 2014

UNE’s Dr. Marissa Betts works on reconstructing Dailyatia, and the sketch above shows how she imagines the creature might have looked. However, no intact Dailyatia has ever been found, so while logic and reasoning can take us part of the way to understanding how this creature used to live, we also know that Dailyatia probably did not look exactly like the picture above.

Here at UNE Discovery, we thought this makes for a fantastic opportunity to let our creativity loose and maybe spark a few new ideas! Our new and improved Palaeontology Puzzles activity takes enlarged replicas of Dailyatia sclerites and allows students to come up with their very own reconstruction of this mysterious animal. Was it long like a snake, or round like a sea urchin? Was it completely covered in shelly armour, or did the soft parts peek through? Did it have feet? These are all questions that Palaeontologists have to answer “We don’t know”. In this type of Palaeontology, coming up with new ideas to test is half the game. By creating little models like this, we can start answering questions like “How do A and C sclerites fit together?” or “How would it move if we placed the sclerites like this?”

Examples of student reconstructions

Science is all about testing ideas and seeing which ones hold up to scrutiny. While many of our ideas often don’t end up working out, by ruling out those possibilities we get closer and closer to the truth. In the case of Dailyatia we may never know exactly how the living creature once looked, but we can keep experimenting with different reconstructions and see what works.

Who knows, you may just be the one to discover the truth of Dailyatia! So don’t forget to ask about the new Palaeontology Puzzles activity when booking your UNE Discovery visit.