Lecture 16 Flashcards
At the top of the
theropod evolutionary novelties
ladder -
The paraves.
para = near aves = birds
This group is comprised of the:
Dromaeosaurs (the raptors)
Troodontids (sister clade of avialae)
Avialae (ancient and modern birds)
The common ancestor to all paraves
evolved no later than
160 Ma during the
Late Jurassic but may have been present earlier than that (Middle Jurassic or perhaps even Early Jurassic).
One evolutionary novelty that
defines the Paraves is their
Retractable
pedal digit II with an enlarged claw (Sickle Claw) that could move in a 180 degree arc
-This novelty is shared by the
dromaeosaurs, troodontids, and early
members of avialae (incl. Archaeopteryx)
Paraves additional Evolutionary Novelties
Other novelties:
* stiffened tail over much of its
length (ossified tendons) yet
flexible at the base
* backward-directed pubis
* larger, elongate skulls with
small, serrated teeth
Dromaeosaurs (‘running lizards’)
Dromaeosaurs are known from all continents.
These include very small members such as Microraptor
Small and medium raptors such as Velociraptor & Deinonychus
Large raptors such as Utahraptor and Austroraptor
See slide (5) for more variety
Microraptor
Microraptor is known from hundreds of fossil specimens, collected in what is now Liaoning, China
Not a bird but a Four winged glider dromeosaur arboreal (tree-dwelling)
wings on arms and rear limbs can be seen on slide 6
Velociraptor
Velociraptor (“swift plunderer”) was
discovered during an AMNH
expedition led by Roy Chapman
Andrews to Mongolia in 1923. (same area where he found the egg-thief lizard)
-The discovery mainly consisted of a
crushed skull and a sickle claw.
- A complete specimen was found in 1971
Fighting Dinosaurs
In 1971 an expedition to Mongolia revealed a complete specimen of Velociraptor.
It was preserved alongside another dinosaur - its broken arm locked in the strong jaws of Protoceratops
Evidence of feathers in Dromaeosaurs can be found:
In the bowed ulna where quill knobs appear
