EASC 103 Test 4

Maniraptorans

“Hand snatchers” that are incredibly diverse, and highly derived coelurosaurs

Maniraptoran characteristics

• bony sternum

• Long forelimbs

• Long hands

• Semi-lunate bone in carpal for flexibility

• Even larger brain size relative to body size

Alvarezsauridae

small, long-legged theropods with short, robust forelimbs and compact, bird-like hands (fused together). Have very rigid wrists and hands. Had lengthened digit 1/hallux. If digit 2 or 3 were present, then they were vestigial.

Ate insects, with claws used to hook and pull when digging

Mononykus

• “One claw”

• Alvarezsauroidea —> Alvarezsauridae —> Parvicursorinae

• known from single specimen found in Mongolia 70Ma

• Facial disc

Facial disc

Feathers around the face in a circular pattern, which are specialized to catch sound and direct it to the ears. Seen on barn owls

Therizinosauria

• theriz = “to reap” or “cut off”

These Maniraptorans are found in Early and Late Cretaceous deposits in Mongolia, China, and western North America

Therizinosauria characteristics

Has characteristics similar to prosauropods:

• long necks

• Wide “pot-bellied” torso

• More upright posture

• Relatively short tail

• Leaf shaped teeth

And also has enormous claws to defend itself and the bring plants towards them

Beipiaosaurus

• named after the city Beipiao in Liaoning

• Found in China Early Cretaceous

• Small basal Therizinosaur with preserved feather integument

• Melanosomes indicate brown coat of long, simple feathers

• Therizinosauria

Therizinosaurid track

Has 4 digits, with the digit 3 curving towards the midline. It still has the theropod notch.

Nothronychus

• “slothful claw”

• Lizard in Arizona/Utah at 92Ma Late Cretaceous

• 3.5m (12ft) tall

• 30cm long claws

• Therizinosauria —> Therizinosauridae

Therizinosaurus

• “scythe lizard”

• Mongolia 70Ma Late Cretaceous

• Has gently curved claws that are 1m in length

• 5m tall