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The members of the order Pelecaniformes are relatively large water birds that are found across the world. Some people erroneously refer to Pelecaniformes as birds with feet and four-toed and which are webbed. This is the main reason why these birds were referred to by the name Steanopodes. Most Pelecaniformes have a bare patch in the throat known as gular patch. The nostrils have undergone evolution; they are now dysfunctional slits. This is why these birds are always forced to breath through their mouths. Their main sources of food are marine life such as squid, and fish. They dwell on colonial nests although individual birds always maintain monogamous family relationships. Their young ones are altricial, meaning that they are naked and helpless immediately after they are hatched from eggs. The evolution of the Pelecaniformes The birds that belong to this order are about 50 in number as far as the “steganopode” circumscription goes. However, modern scientists say that convergent evolution has resulted in very many similarities. The wealth of evidence that is present has resulted in a split that made the pelecaniformes to be divided into even smaller groups. Most of the lineages under discussion here include gannets, anhingas and cormorants. These lineages constitute a very natural group. The name phalacrocoraciformes has been recently proposed to give to these natural members of a common lineage. The prevailing relationships between different tropical birds are not clear but the lineage seems to be very distinct. The Pelecaniformes lineage Hybridization studies involving the use of DNA specimens have resulted in placement of families that were traditionally considered distinct to be within the holistic scope of Pelecaniformes family. This means that the Pelecaniformes were put together with ibises, grebes, spoonbills, storks, albatrosses, loons and petrels. This was a very radical move Recent studies suggest that there are very subtle similarities between members of Pelecaniformes as defined traditionally merely because of convergent evolution. The cause of similarity is not a common descent. Members of this group are also paraphyletic. In the revised conception of Pelecaniformes, it is only a handful of species that fall perfectly into this category. There has been a very nagging problem of placing specific member of this group into the right family owing to the fact that very little is known about the prehistoric forms of every respective family member. The Pelecaniformes lineage seems to have its roots at the end of Cretaceous. Whether they are monophyletic or not, these birds appear to be members of a very close-knit group that can best be described as “higher water birds”. This group also includes Procellariiformes and penguins. The most interesting thing about Pelecaniformes is that fossil bones that are in the K-Pg boundary cannot be accurately placed in any of the orders that cause confusion. Rather, they contain traits that are characteristic of all of these orders. This is the main reason why several theories exist to try to explain these similarities. The order Elopterygidae has been proposed in order to take care of Cretaceous Pelecaniformes.
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