Croaking Science: Evolutionary Origins Part 2- The Rise of the Reptiles

Becky Austin our Croaking Science Volunteer, finds out about the evolutionary origons of reptiles this week in part two of our evolution series.

By around 340mya, amphibian life was flourishing, as evolution from fishes for life out of water was advancing rapidly. However these animals were still dependant on water, as amphibian eggs had to be laid in water in order to avoid them drying out. Terrestrial life was therefore restricted only to areas near water sources, leaving vast inland areas unoccupied by vertebrate life.

This all changed when a group of animals known as the reptilomorphs evolved in the Carboniferous period. These animals were, put simply, half way between amphibians and reptiles, and were the precursors to reptilian life. But at what critical point did an amphibian become a reptile?

The most important feature that defines a reptile, besides its scaly skin to cope with water loss on land, is the ‘amniote egg’. The first true reptiles could lay this type of egg, which allowed gas exchange with air through a robust membrane (the shell) whilst avoiding drying out. This meant that reptiles could thrive without need to return to water to reproduce, allowing colonisation of the rich and vast inner land masses in a time where the climate was becoming more arid.

It will probably never be known at what specific time this transition first occurred, but there have been a number of fossil discoveries which give us a general idea. One of these was found close to home, at the East Kirkton quarry in Scotland, and is called Westlothiana lizziae. The reptilomorph species was present around 335mya, and resembled a small lizard. Another Scottish fossil, Casineria, is very similar, with skeletal structures suggesting a very terrestrial lifestyle. It is therefore possible that the first reptiles were small creatures like these, whose pioneering steps into fully terrestrial life would lead to the evolution of all amniotes, including dinosaurs, birds and mammals. 



References:

Paton, R.L., Smithson, T.R and Clack, J.A. (1999). An amniote-like skeleton from the Early Carboniferous of Scotland. Nature, vol. 398 pp. 508-513.

Smithson, T.R, Carroll, R.L, Panchen, A.L and Andrews, S.M. (1993). Westlothiana izziae from the Viséan of East Kirkton, West Lothian, Scotland, and the amniote stem. Transactions of the Royal Society of Edinburgh:  Earth Sciences, vol. 84, issue 3-4, pp. 383-412.

What you can do:

Reptiles are believed to be under recorded in some parts of Scotland. Why not help increase local records by using the free Dragon Finder App to get your records to Froglife.

 

Scottish amphibians and reptiles thrown a lifeline by the Heritage Lottery Fund

Wildlife conservation charity Froglife has received exciting news that The Heritage Lottery Fund has awarded a grant of £422,400 for Scottish Dragon Finder.  This exciting new project will directly involve 28,000 people in conserving Scotland’s amphibian and reptile species, with activities taking place all over the country in the next four and a half years. 

There are ten native amphibian and reptile species in Scotland, seven of which feature as priority species in the UK Biodiversity Action Plan. There is an urgent need for more data on where the animals are and their populations, with current evidence suggesting the creatures are in decline.  Dragon Finder will introduce thousands of new people to the intriguing lives of amphibians and reptiles, teaching them how to survey, record and protect these amazing animals. 

Colin McLean, Head of the Heritage Lottery Fund in Scotland, said:

“This year, the Year of Natural Scotland, brings into focus the natural beauty and biodiversity that surrounds us. It is one of our greatest national assets, attracting visitors from home and abroad and making a valuable contribution to our tourist economy.

“We have some incredible native wildlife in Scotland but our species and habitats are under constant threat. Recent reports such as State of Nature and the Scottish Government’s 2020 Challenge for Scotland’s Biodiversity plan highlight the need to act now if we are to protect it. We hope that with the Heritage Lottery Fund support announced today, communities across the country will be inspired and empowered to safeguard the existence of these rare creatures.”

Common Lizard (Zootoca vivipara)

Scottish Dragon Finder will involve communities, school children, gardeners and hill walkers in improving fresh-water ponds across 14 local authority areas, identifying and recording the current amphibians and reptile populations and in learning activities to raise awareness of the endangered species and the role they play in the country’s biodiversity.  It is an expansion of London Dragon Finder, which has been running in the City for just under a year.

 

Kathy Wormald, Froglife’s CEO added:

 

“We are thrilled to be bringing our innovative Dragon Finder project to Scotland.  We will be introducing people who have never seen these animals before to the wonders on their doorstep, and encouraging those who spend a lot of time outdoors to let us know when they see amphibians and reptiles through our free app.  We’ll be hosting some really creative educational activities and hosting trainee placements, alongside work to create and restore habitats across Scotland.”

 

Creative activities will celebrate Scottish 'Dragons'

 

Ron Macdonald, Scottish Natural Heritage's Head of Policy and Advice was just as excited with the good news for the nation’s wildlife: 

 

"We look forward to supporting Froglife in this great opportunity for the conservation of amphibians and reptiles across Scotland."

 

Great Crested Newt (Triturus cristatus )

• Find out more about Froglife's Dragon Finder project at the Living Atlas website here, where you can also download the free app
• Learn more about Froglife's work in Scotland at the Froglife website here
• Help co-fund Froglife's work and enable us to restore even more habitats by donating to the Save our Dragons appeal and texting NEWT13 followed by a donation of £2-10 to 70070  

Photos: Sivi Sivanesan, Sam Taylor and Silviu Petrovan