Historic life-size dinosaur sculptures at London's Crystal Palace Park have been labelled "at risk" and in danger of losing toes, teeth and tails.

The 30 Grade I-listed statues, constructed in the 1850s, have been added to Historic England's Heritage at Risk Register after experts found large cracks on the bodies and limbs.

The cause of the damage is not yet known but it is thought ground movement on the park's artificial islands, where the dinosaurs are located, and the changing water levels in the surrounding lakes is the cause.

Significant conservation work was carried out in 2003 and 2016-17 but a "major" research project and survey is thought to be needed to understand the reasons for the deterioration.

Dr Ellinor Michel, chairwoman of the Friends of Crystal Palace Dinosaurs group which fundraises for the conservation of the statues, said: "We've been working for years to improve the future for this site, which is one of the most important in the history of science, with the support of many thousands of dinosaur friends locally and around the globe.

"Whilst it is distressing that the sculptures need to be called 'at risk', it is the best way for them to get the professional conservation work they need. Thank you, Historic England; the future suddenly looks brighter for the birthplace of 'Dinomania'."

The dinosaurs in the park stand in chronological order - from the oldest land animals known from fossils found by the Victorians, such as the Dicynodons, to the the marine reptiles found by famous fossil collector Mary Anning.

At the time of the sculptures' creation in 1852-5 by Benjamin Waterhouse, the term "dinosaur" had only been coined 10 years previously and bringing life-size extinct animals to the general public was seen as "radical".

"These wonderful creatures are in a state of disrepair and require significant conservation works. We don't want them to become extinct again!," said Duncan Wilson, chief executive of Historic England.

"By adding them to our Heritage at Risk Register, we can focus attention on them and ensure a lasting programme of repairs and on-going maintenance is carried out.

"Working in partnership with Bromley Council and the Friends of Crystal Palace Dinosaurs, we hope to secure their long-term future."

The Heritage at Risk Register is a programme that helps experts understand the overall state of England's historic sites and identifies those that are most at risk of being lost as a result of neglect, decay or inappropriate development.