Thursday, July 30, 2015

Raptors Extinct and Extant

While working at World Bird Sanctuary’s Stone Zoo bird show in Boston, I have learned to make three major distinctions indicative of raptors: excellent eyesight, strong grasping feet and a sharp, curved beak.

Steven Spielberg’s Jurassic Park has made Velociraptors famous, but what do these prehistoric “raptors” have in common with modern raptors? They certainly don’t have a curved sharp beak or grasping feet.

It turns out Velociraptors and other theropod dinosaurs with raptor in their name such as Oviraptor or Eoraptor aren’t even closely related.  However they are united under the Maniraptoran clade, which means “seizing hands,” a nice parallel to extant (meaning living today) raptors’ seizing feet. They are defined as being more closely related to birds than other dinosaurs.

Dromaeosaurid (photo: wikipedia by Tom Parker)

Dromaeosaurs, or “running lizards,” are a group of Maniraptors containing Velociraptors and other “true” prehistoric raptors defined by their large grasping hands, a stiffened tail and one large, slashing claw on each foot. Modern birds of the Aves class are the sister group to Dromaeosaurs. You can compare an artists’ rendition of an extinct  raptor to our extant raptor, Diablo the Tawny eagle below.

Today we have many different raptors within Aves, which belong to different groups as well. The orders Accipitriformes, Strigiformes and Falconiformes are an example of convergent evolution and each produced unique raptor species.

Accipitriformes is the most diverse raptor order consisting of many different families of eagles, hawks, harriers, kites, osprey, the secretary bird and Old World vultures.  New World vultures of the Americas are not related to Old World vultures of Africa, Europe and Asia.  They have merely evolved to fulfill similar ecological niches.

Osiris, the Egyptian Vulture is an Old World Vulture (photo: Gay Schroer)

Baton Rouge, a King Vulture, is a New World Vulture (photo: Gay Schroer)

New World vulture phylogenic placement has proven to be difficult with DNA evidence supporting their inclusion in both the bird orders of Accipitriformes and Ciconiiformes or storks. Old World vultures are true raptors, while New World vultures lack the strong grasping feet of raptors. You can make this comparison between Osiris the Egyptian vulture (Old World) and Baton Rouge the King vulture (New World) at our Stone Zoo bird show.

Riley, a Barn Owl (photo: Aurora Potts)

Strigiformes consist of two main families of owls; barn owls and typical owls. Owls are mostly nocturnal and are therefore more sound sensitive than other raptors. Barn owls belong to the family Tytonidae.  Their face is heart-shaped and their legs are longer than that of Strigidae owls. Typical owls belong to the more varied family, Strigidae. You can see these distinctions on Riley the American Barn owl and Reese the Great Horned owl at our Stone Zoo bird show.

Reese, a Great Horned Owl (photo: Aurora Potts)

Naturally, Falconiformes are falcons, which are more closely related to songbirds and parrots than they are to any other raptor (believe it or not). Falcons are the speedy and agile birds of prey that use their tomial tooth at the end of their beak to break their prey’s spine. You can see the notch that is the tomial tooth on this Peregrine falcon on exhibit at Stone Zoo.

A Peregrine Falcon on exhibit at Stone Zoo

Even though extinct and extant raptors are hardly related, you can see all these fascinating predators possess many adaptations.   Their unique characteristics allow for a wide variety of species to share the generally speedy seizing and grasping raptorial name in prehistoric times and up to modern day.

Submitted by Aurora Potts, Naturalist/Trainer for World Bird Sanctuary’s Stone Zoo Show

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