Post #13886

Hoatzin: Anatomy of a Dinosaur. This bird is closest to the terrible lizards in structure and behavior When I look at the hoatzin, I get a strange feeling. I keep thinking I see a scaly raptor with a thin layer of feathers over it for camouflage. But another moment will pass, and he will throw them off to hiss in a reptilian manner, announcing the onset of a new era of dinosaurs. And there really is something in this, because the hoatzin is the most dinosaur-like bird of all living creatures! Those who read us on a regular basis are already aware that birds are real dinosaurs, and not their descendants, as previously thought. They are still full of features and traits that were widespread among the terrible lizards of the Mesozoic. But they still lost some features. For example, in the process of specialization of wings, they abandoned the claws on the front paws, and the ability of dinosaurs to feed on leaves, fermenting them in their gastrointestinal tract, sank into oblivion along with sauropods - huge and clumsy herbivorous dinosaurs. And the hoatzin is the only one that has retained both of these features, at least in part. Hoatzin chicks are unusually dexterous and agile by bird standards. Almost immediately after birth, they are able to crawl along the branches of their native tree and even escape from danger by... jumping into the water! After which they successfully swim to the shore and return to their nest again - and all thanks to the claws on their paws, which fall off as they grow up. But along with its claws, the hoatzin also retained many much more primitive features. Its keel is poorly developed, the muscles of the wings work poorly, and the skull is heavier and more massive than that of other flying birds. Therefore, all day long he sits in the crown of trees and feeds on their leaves, the fermentation of which takes a lot of strength and energy of the body. All this, together with its strange appearance, gives the hoatzin the image of a bird that is just a few steps away from the ancient dinosaurs. But this is not true, we were misled. The hoatzin is certainly an ancient and unique bird, whose evolutionary branch split off from the general bird lineage approximately 66 million years ago. And yet it is included in the subclass of new palate birds, which arose not so long ago, at the very end of the Cretaceous period. The real oldies are ancient palatine (read correctly!) birds that separated from the common branch 70-120 million years ago. And, despite their antiquity, all these ostriches, emus and tinamous are much less like dinosaurs than hoatzins. But this is not surprising, because all the “dinosaur” features of the hoatzins are a remake. Their keel and muscles have degraded to give way to a huge crop that occupies a large part of the chest. And following them, the skull also changed - after all, it should be light only if you fly all day long. And even claws - the main advantage of hoatzins - are no