Monday, September 22, 2014

Rhamphorhynchidae to Scansoriopterygidae

I suggest that Rhamphorhynchidae (basal pterosaur group) is the ancestor of Scansoriopterygidae (basal paraves group).

Scansoriopterygidae are basal paraves with flight feathers on the arms and legs.
Scansoriopterygidae (or a group very much like it) is the ancestor of the later Paraves such as Microraptor, Archaeopteryx etc.
Rhamphorhynchidae pycnofibres are homologous (ancestral) to Scansoriopterygidae feathers.
The Rhamphorhynchidae long bony tail is homologous to the Scansoriopterygidae long bony tail.
The Rhamphorhynchidae caudal rods are homologous to the Scansoriopterygidae caudal rods.

The Scansoriopterygidae elongate outermost digit is transitional between Rhamphorhynchidae and later Paraves.
The Scansoriopterygidae wing feathers replaced the function of the wing membrane of their pterosaur ancestor. The membrane close to the arm (patagium) remained.
The Scansoriopterygidae hindwing feathers replaced the function of the uropatagium of their pterosaur ancestor.
The Scansoriopterygidae propatagium IS the propatagium from their pterosaur ancestor.

Scansoriopterygidae is one of the most basal (primitive) members of paraves.
It used the same muscles as pterosaurs for flying. It could splay its hind limbs like pterosaurs for flying.
The evidence strongly supports the transition from pterosaur to basal paraves, with Scansoriopterygidae being transitional.


  1. For later reference of what?

    1. To include the synsacrum in the chart of differences later.
      Related to this:

  2. For later reference:

  3. For later
    For instance, Archaeopterix has a wishbone (furcula) and bird-like feet. This means that it is not merely a feathered dinosaur but something quite different. There are other differences between dinosaurs and birds: Dinosaurs had serrated teeth, while birds have peg-like teeth. Bird feet have reversed toes used for perching in branches--something no dinosaurs has been seen to have. Meanwhile, dinosaurs had a characteristic joint in their lower jaws for grasping prey--something never found in birds.

  4. Jingmai K. O’CONNOR Corwin SULLIVAN
    Similarities among a number of basalmost paraves:
    "The recently described maniraptoran theropod Zhongornis haoae, known from a single
    juvenile specimen, was originally identified as a bird. However, morphological re-evaluation reveals
    striking resemblances to both Oviraptorosauria and Scansoriopterygidae. The reduced, but still long,
    boney tail is reinterpreted as having approximately twenty vertebrae and is reminiscent of the tails of
    Caudipteryx and Epidexipteryx in its proportions and morphology. Other morphological similarities
    with basal oviraptorosaurs include a short and deep skull, and a reduced minor digit. Zhongornis
    also differs strikingly from other Mesozoic birds, and resembles scansoriopterygids, in the size of
    the alular metacarpal, the proportions of the manual digits, and the lack of processes on the ischium.
    These similarities, together with resemblances between basal oviraptorosaurs and previously described
    scansoriopterygids, may point to a close relationship between these two clades. Cladistic analysis
    confirms a close relationship between Zhongornis and Scansoriopterygidae, which share forelimbs
    and pedal unguals that are elongate compared to those of oviraptorosaurs, but does not support
    oviraptorosaur affinities for this clade. Additional specimens will be required in order to determine
    both the taxonomic placement of this species and the affinities of Scansoriopterygidae, highlighting the
    drawbacks of basing new species on juvenile material."