Hylonomus Returns Home

Oldest Reptile Fossil Returns to Nova Scotia

The coal deposits of Nova Scotia, laid down in the Carboniferous Geological period, some 310 million years ago, preserve a remarkable fossil record of the swamps and forests of this ancient time in Earth’s history.  Giant clubmosses and horsetails shared the landscape with strange tree-like Sigillaria and tall Lepidodendrons.  The climate was equatorial and the fossils at perhaps the most important site in Nova Scotia (Joggins, 150 miles north-west of Halifax) also preserve evidence of the animals that lived in this swampy domain.

More than 190 fossil skeletons of small amphibians and reptiles have been discovered at the Joggins site.  The Joggins cliffs were declared a World Heritage site by UNESCO in 2008, such is their importance to science.  Now one of the best preserved fossils of a tiny reptile, no more than 20 centimetres long is being returned to Canada for the first time since it was sent to London, more than a Century ago.

The fossil is of Hylonomus lyelli an insect eating reptile, that is believed to be one of the first of its kind.  Its head was proportionally much smaller than the amphibians from which it was descended.  However, the structure of the skull shows a significant advance over an amphibian skull as it allowed more space for the attachment of stronger jaw muscles.

An Illustration of Hylonomus

Picture Credit: Kingfisher

This fossil was uncovered by Nova Scotian geologist John William Dawson in 1859 but was handed over to the British Museum around the turn of the century. The British Museum is now known as the Natural History Museum.  The fossil is going to be on display at the Joggins Fossil Centre for the next six months.

The Joggins Fossil Centre’s chief palaeontologist Melissa Grey commented:

“If you look closely, you can see elements that you would recognise.  Bits of the jaw with teeth and the backbone and the tail and some of the legs as well.”

The fossil is so delicate and precious, it had to be delivered by hand.  Such a cargo cannot be trusted to even the most conscientious of courier firms.  A number of small reptile and amphibian fossils have been discovered at the site, many have been recovered from the tree-sized stumps of large Carboniferous plants.  How or why these creatures ended up preserved in the remains of ancient plants is a mystery.  A number of theories have been proposed, for example these small vertebrates may have made such tree stumps their homes.  Or perhaps small creatures fell into the rotten stumps and found themselves stuck, unable to crawl out again – an example of a natural “bottle trap”.

Whatever the explanation, these fossils are very important to scientists as they attempt to piece together the story of how vertebrates came to conquer the land.

Melissa added:

“This is the world’s oldest known fossil reptile.  So it is very important to our understanding of vertebrate life, animals with a backbone and that includes us.”

The fossil will form part of a special display and will be on show until October 31st.

5 Responses to “Hylonomus Returns Home”

  1. Max Farjon in the Netherlands says:

    I am looking for a photograpf of a fossil that shows the bones of a fore limb of the reptile Hylonomus I very much would appreciate to become in possesion of such a photograph

    • Mike says:

      We do not have any photographs of the fore limb, however, you can contact Melissa Grey (curator) at the centre based around Joggins Fossil Cliffs and she may be able to furnish you with such a thing – curator@jogginsfossilcliffs.net. Alternatively, there is a good site called reptileevolution.com which has a cladistic approach and may have some line drawings of Hylomomus forelimb material – hope this helps.

      Team Everything Dinosaur

  2. Max Farjon in the Netherlands says:

    I do not know what to add or change in my message

  3. Daniel says:

    Quick question- what amphibian did this reptile descend from?

    Yours sincerely,
    Daniel

    • Mike says:

      Not really a quick question, Hylonomus lyelli is regarded as one of the world’s oldest true, egg-laying (amniote) reptiles. Although, some scientists have argued that this is actually an amphibian. There is a lot of debate over the evolution of the two major groups of amniotes (one group contains the lineage that would lead to mammals), the second group consists of reptiles and the birds. Since the first paper on this animal found in the Late Carboniferous coal deposits of Nova Scotia (paper published around 1860), there has been argument over the phylogenetic relationship between Hylonomus and whether it relates to the synapsids (the path to the mammals) or the diapsids (path to Archosaurs, most reptile groups today and the birds). Our view is that Hylonomus is a reptile, canine teeth in the upper jaw etc, it is more advanced than the Reptilomorphs from which it is very probably descended. We think that, based on the papers we have read, that Hylonomus be an early diapsid, so it would have been descended from Reptilomorphs that gave rise to the Diapsid lineage.

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