The mass death of dinosaurs and other ancient animals in Madagascar was associated with the poisonous "bloom" of water.
The northwest of Madagascar is home to some of the richest deposits of ancient fossils. The Mevarano Formation is a series of vast tombs containing the remains of dinosaurs, crocodiles and ancestors of birds that lived here about 70 million years ago. According to local paleontologist Raymond Rogers, in one area three times the size of a tennis court, he and his colleagues were able to identify the remains of about 1,200 different species.
What caused this mass death? It is assumed that a prolonged drought, against the background of which short but extremely powerful downpours took place, could be to blame. They created temporary streams of water that carried the remains of dead animals together and covered them with silt. On the other hand, not everyone agrees with this. The position of the bones shows that, most likely, the animals were buried in the same place where they died. Everything happened quite quickly - the unknown killer was equally dangerous for flying, and for crawling, for predatory and herbivores.
At the recent annual meeting of the Society of Vertebrate Paleontology, Rogers announced a new, unusual version. According to him, the arched posture, which was preserved by the remains, may indicate dying convulsions, and deposits of carbonates - an active growth of algae. Such a "bloom" is quite capable of causing the mass death of animals that come to the watering hole and simply live in the water. Suffice it to say that dinoflagellates and cyanobacteria secrete saxitoxin, an extremely dangerous compound that is fatal to humans already in an amount of 0.14 mg.
For example, in the Miocene epoch in the sea on the territory of the present state of Chile, such a "death" happened more than once: water with toxic algae caused the death of whales and fish, whose skeletons are now in the Atacama Desert. There are suspicions that algae have caused the formation of some other sites rich in paleontological finds. Unfortunately, so far no direct evidence of this - reliable traces of algae - has been found.
Sergey Vasiliev