After 200 million years, all-male future spells doom for reptiles
A group of reptiles called tuataras, the only surviving order that were around when dinosaurs roamed the earth could be wiped out because climate change could turn all the eggs into males - causing them to not be able to reproduce.
The gender of tuataras, an ancient type of reptile with three eyes, is determined by the temperatures that the embryos are kept at when in the egg. Global warming means that the reptiles, regarded as living fossils, face the threat of dying out in the wild because of a terminal shortage of females.
Only males will be born in nests where the eggs have been kept at temperatures of 22.25C (72.05F) whereas females are guaranteed only at temperatures lower than 22.1C.
Modelling showing the likely impact of climate change on the last remaining homes of tuataras showed that the last female could hatch by 2085 for at least one of the two surviving species.
Tuataras evolved 225 million years ago. The two remaining species cling on to survival in New Zealand and are regarded as among the oddest reptiles. They have a mysterious third eye at the top of their heads, are able to hold their breath for an hour and, despite their cold-blooded nature, are nocturnal.
Until rats and other mammals - introduced by humans - arrived, the reptiles were widespread in New Zealand but they are now found only on a handful of small islands safe from the mainland.
With climate change, average temperatures are expected to rise by up to 4C (7.2F) by 2085, which would be enough to ensure that all the North Brother Island tuataras, Sphenodon guntheri, are hatched male. The other species, the Cook Strait tuatara, S. punctatus, could follow soon afterwards.
Stories like this just make me so sad.
The tuatara is an amniote of the family Sphenodontidae, endemic to New Zealand. The two species of tuatara are the only surviving members of the Sphenodontians which flourished around 200 million years ago, and are in the genus Sphenodon. Tuatara resemble lizards, but are equally related to lizards and snakes, both of which are classified as Squamata, the closest living relatives of tuatara. For this reason, tuatara are of great interest in the study of the evolution of lizards and snakes, and for the reconstruction of the appearance and habits of the earliest diapsids (the group that additionally includes birds and crocodiles).
Tuatara are greenish brown, and measure up to 80 cm (32 in) from head to tail-tip with a spiny crest along the back, especially pronounced in males. Their dentition, in which two rows of teeth in the upper jaw overlap one row on the lower jaw, is unique among living species. They are further unusual in having a pronounced parietal eye, dubbed the "third eye", whose current function is a subject of ongoing research. They are able to hear although no external ear is present, and have a number of unique features in their skeleton, some of them apparently evolutionarily retained from fish. Although tuatara are sometimes called "living fossils", recent taxonomic and molecular work has shown that they have changed significantly since the Mesozoic era.
They have a really rare 'third eye', which makes them even more unique and special.
The ‘third eye’ is visible under young tuatara’s skin and becomes covered with scales after four to six months. The ‘third eye’ soaks up UV (ultra violet) rays in the first few months of the tuatara’s life. The young tuatara get Vitamin D from the UV rays, which helps them grow into healthy adult tuatara.
Some weird facts about them:
They are capable of holding their breath for nearly an hour Tuatara have one of the slowest growth rates of any reptile Tuatara keep growing until they are about 35 years old They will share burrows with birds, but a male might bite off a baby bird’s head if it is hungry – which doesn’t make it a very good house guest! Male tuatara can weigh up to 1500grams A tuatara’s average life span is about 60 years but they can live to be over 100 years old At an average of 50cm long, the tuatara’s size today is maybe only half of what it once was Like other reptiles, tuatara are cold-blooded, which means their temperatures change with the air temperature. Tuatara are nocturnal and prefer cool weather. However they will often bask in the sun to warm their bodies – but they are careful not to over-heat. Young tuatara usually hunt for food during the day – to avoid being eaten by adult tuatara at night!