Sunday, October 4, 2015


The ancestor of primitive birds was a rhamphorhynchoid pterosaur much like Jeholopterus or Pterorhynchus.
The earliest primitive birds were the feathered, flying creatures with long-bony-tails, such as the scansoriopterygids.
The scansoriopterygids would have lived alongside synapsids such as the aquatic Castorocauda and arboreal gliding mammal Volaticotheriumthe rhamphorhynchoid pterosaurs Jeholopterus and Pterorhynchus, as well as a diverse range of insect life (including mayflies and beetles) and several species of salamander.[14][15]
The [Epidendrosaurus] material described in this paper was collected from a new locality, Daohugou, in east Nei Mongol, northeast China, which is west of Liaoning Province. Many salamanders(Wang 2000), plants and insects (Zhang 2002)have recently been discovered from this new locality. It is notable that an anurognathid rhamphorhynchoid pterosaur [Jeholopterus] with beautiful hair [pycnofibers] covering the whole body has also been reported from this locality (Wang et al. 2002). The estimated age of the deposit at this locality is very controversial and ranges from the Middle Jurassic or the Early Cretaceous according to various authors (Wang etal. 2000; Zhang 2002); however, most workers currently regard it as being Late Jurassic.
Two other Chinese specimens were reported with integumental covering, coming from the same stratum (the Daohugou Bed) as Jeholopterus. So far we have not had the opportunity to examine this material. The first one is a small unnamed anurognathid with extensive preservation of soft tissue, including fibres that have been interpreted as protofeathers (Ji & Yuan 2002). The published pictures show that the soft tissue interpreted as protofeathers is of the same nature as the pycnofibres of Jeholopterus.
At least some pterosaurs had hair-like filaments known as pycnofibres on the head and body, similar to, but not homologous (sharing a common structure) with, mammalian hair. Though a fuzzy "integument" (natural covering/outer coat) "was first reported in 1831" by Goldfuss,[29] recent pterosaur finds and the technology for histological and ultraviolet examination of pterosaur specimens have provided incontrovertible proof: pterosaurs had pycnofibre coats. Pycnofibres were not true hair as seen in mammals, but a unique structure that developed a similar appearance. Although, in some cases, actinofibrils (internal structural fibres) in the wing membrane have been mistaken for pycnofibres or true hair, some fossils such as those of Sordes pilosus (which translates as "hairy demon") and Jeholopterus ninchengensis do show the unmistakable imprints of pycnofibres on the head and body, not unlike modern-day bats, another example of convergent evolution.[21] The head-coats do not cover the pterosaur's large jaws in many of the specimens found so far.[29]
Jeholopterus was a small anurognathid pterosaur from the Middle to Late Jurassic[1] Daohugou Beds of the Tiaojishan Formation of Inner MongoliaChina , preserved with hair-like pycnofibres and skin remains.
We report a new and nearly completely articulated rhamphorhynchoid pterosaur, Jeholopterus ningchengensis gen. et sp. nov., with excellently preserved fibres in the wing membrane and “hairs” [pycnofibers] in the neck, body and tail regions. Many of its characteristics such as a short neck, short metacarpals and distinctively long fifth pedal digit are characteristic of rhamphorhynchoids. The new species can be further referred to the ‘strange’ short-tailed rhamphorhynchoid family Anurognathidae. It is much more complete than the other known members of the family, namely, Anurognathus from Solnhofen, Germany, Batrachognathus from Karatau, Kazakhstan, and Dendrorhynchoides from Beipiao, Liaoning Province, China. The new pterosaur also shows that the wing membrane is attached to the ankle of the hind limb. The pedal digits are webbed. Furthermore, the “hair” of Jeholopterus bears some resemblance to the hair-like integumental structures of the feathered dinosaur Sinosauropteryx although there is yet no direct evidence to argue for or against their homology.
A new rhamphorhynchoid [Pterorhynchus] is described with a headcrest that is unprecedented among the long-tailed pterosaurs. The preservation of the headcrest presents significant implications regarding the physical appearance and aerodynamics of all pterosaurs. Also, "hair-like" integumentary structures of this pterosaur are shown to be complex multi-strand structures which presents evidence on the origin of feathers and the possibility of a remarkably early ancestral relationship between pterosaurs and birds.
Pterorhynchus was a genus of rhamphorhynchid "rhamphorhynchoid" pterosaur from the Middle or Late Jurassic-age Daohugou Formation[1] of Inner Mongolia,China.
This type specimen consists of an articulated, nearly complete skeleton with remains of the integument. These included the wing membrane, hair-like structures, a long version of the vane found at the end of "rhamphorhynchoid" tails, and a head crest with both a low bony base and a large keratin extension; the latter feature is unusual in "rhamphorhynchoids" (i.e. basal pterosaurs), the fossils of which do not often show head crests.
The hairs (pycnofibers) were originally described as pinnate, with many strands arising from a single base (calamus), and seen as corresponding to the hypothetical Stage II in the evolution of feathers.
The only known Yi qi fossil was found in rocks assigned to the Tiaojishan Formation, dating to the Callovian-Oxfordian age of the Middle-Late Jurassic,[1] dated to between 165 and 153 million years ago.[3] This is the same formation (and around the same age) as the other known scansoriopterygids Epidexipteryx and Scansoriopteryx.
Darwinopterus (meaning "Darwin's wing") is a genus of pterosaur, discovered in China and named after biologist Charles Darwin. Between 30 and 40 fossil specimens have been identified,[1] all collected from the Tiaojishan Formation, which dates to the middle Jurassic period, 161-160.5 Ma ago.[2] The type species, D. modularis, was described in February 2010.[3] D. modularis was the first known pterosaur to display features of both long-tailed ('rhamphorhynchoid') and short-tailed (pterodactyloid) pterosaurs, and was described as a transitional fossil between the two groups.[4] Two additional species, D. linglongtaensis and D. robustodens, were described from the same fossil beds in December 2010 and June 2011, respectively.[5][6]
Darwinopterus, like its closest relatives, is characterized by its unique combination of basal and derived pterosaurian features. While it had a long tail and other features characteristic of the 'rhamphorhynchoids', it also had distinct pterodactyloid features, such as long vertebrae in the neck and a single skull opening in front of the eyes, the
nasoantorbital fenestra (in most 'rhamphorhynchoids', the antorbital fenestra and the nasal opening are separate).[5]
Turner et al 2012.

For reference:
The Rhamphorhynchoidea forms one of the two suborders of pterosaurs and represent an evolutionary grade of primitive members of this group of flying reptiles. This suborder is paraphyletic in relation to the Pterodactyloidea, which arose from within the Rhamphorhynchoidea, not from a more distant common ancestor.
Plieninger, 1901
Included groups





  1. Well, if you want Jeholornis and Oviraptorosauria to be sister taxa, that works out fine from a ghost-lineage perspective because Jeholornis is about the same age as the oldest known oviraptorosaurs.

    Jeholornis were relatively large, primitive avialans, with a maximum adult length of up to 80 cm (2.6 ft).[2] Their skulls were short and high, similar to other primitive avialans like Epidexipteryx and to early oviraptorosaurs like Incisivosaurus.

    Some paleontologists, like Paul Sereno, consider the enigmatic alvarezsaurids to be close relatives of the ornithomimosaurs and place them together in the superfamily Ornithomimoidea (see classification below).

    THE Late Cretaceous rocks of Mongolia have produced unusual and phylogenetically important dinosaurs1,2. Here we report a startling new example, Mononychus olecranus gen. et sp. nov., an avialian theropod dinosaur with a short, robust forelimb possessing a single stout claw. Several features, including a carinate sternum and reduced fibula, suggest that Mononychus olecranus is more closely related to modern birds than is Archaeopteryx lithographica. The two skeletons are among the best preserved fossils known of a primitive bird, and emphasize the complexity of the morphological transformation from nonavialian theropods to modern birds. The occurrence of such a primitive bird in the Late Cretaceous reflects the paucity of Mesozoic bird fossils and suggests that the early radiation of avialians is only beginning to be sampled.

    These mistaken assignments of alvarezsaurs to birds were caused primarily by features that are strikingly, or even uniquely, avian. The sternum, for example, is elongated and deeply keeled for an enlarged pectoralis muscle, as it is in neognathous birds and volant ratites. One bone in the skull of Shuvuuia appeared to be an ectethmoid fused to a prefrontal. The ectethmoid is an ossification known only in Neornithes. Other birdlike characters included the palatine, foramen magnum, cervical and caudal vertebrae, and many others.[10]



    A review of dromaeosaurid systematics and paravian phylogeny. (Bulletin of the American Museum of Natural History, no. 371)
    Turner, Alan H. (Alan Hamilton); Makovicky, Peter J.; Norell, Mark.

    “Epidexipteryx resembles basal oviraptorosaurs
    in several respects, particularly
    in its cranial morphology. Zhang et al. (2008)
    noted some of these, drawing attention to
    the anteroposteriorly short but dorsoventrally
    tall skull, the posterodorsally displaced
    naris and anteroposteriorly long parietals.
    Likewise, the highly procumbent anterior
    dentition and the slightly downturned mandible
    compares favorably to basal oviraptorosaurs
    like Incisivosaurus, Caudipteryx, and
    putatively Protarchaeopteryx.
    Constraining Epidexipteryx as a basal oviraptorosaur

    requires only one additional step in our dataset (fig. 75).”

    Furthermore, the Alvarezsauroidea had simplified homogenous dentition, convergent with that of some extant insectivorous mammals. More recently, they have been placed within the Coelurosauria basal to the Maniraptora or as a sister taxa of Ornithomimosauria within the Ornithomimiformes.
    Some paleontologists, like Paul Sereno, consider the enigmatic alvarezsaurids to be close relatives of the ornithomimosaurs and place them together in the superfamily Ornithomimoidea (see classification below).

    Perle et al. (1993) described the next alvarezsaur to be discovered, naming it Mononychus olecranus (meaning "one claw"). A month later they changed the genus name to Mononykus, because the earlier spelling was already the genus name of an extant butterfly.[5] Perle et al. (1993) mistakenly described Mononykus as a member of Avialae, and one more advanced than Archaeopteryx. They argued that the family Alvarezsauridae was actually a group of Mesozoic flightless birds on the basis of derived features that were unique to birds.[6] Novas (1996) described another member of the class called Patagonykus puertai.[7] Karhu and Rautian (1996) described a Mongolian member of the family; Parvicursor remotus.[8] Chiappe et al.(1998) described another Mongolian member, Shuvuuia mongoliensis and mistakenly found it to be even more derived, concluding that the alvarezsaurs were actually crown-group (that is, modern) birds.[9]

    With the benefit of hindsight it is easy to see that if fossils of the small flying dromaeosaurs from China had only been discovered before the larger flightless dromaeosaurs like Deinonychus or Velociraptor were found, the interpretations of the past three decades on how birds are related to dinosaurs would have been significantly different. If it had already been established that dromaeosaurs were birds that could fly, then the most logical interpretation of larger flightless dromaeosaurs found afterwards would have to be that they represented birds, basically like the prehistoric equivalent of an Ostrich, which had lost their ability to fly.

    Czerkas also believed that Cryptovolans [a dromaeosaurid] may have been able to fly better than Archaeopteryx, the animal usually referred to as the earliest known bird. He cited the fused sternum and asymmetrical feathers, and argued that Cryptovolans has modern bird features that make it more derived than Archaeopteryx. Czerkas cited the fact that this possibly volant animal is also very clearly a dromaeosaurid to suggest that the Dromaeosauridae might actually be a basal bird group, and that later, larger, species such as Deinonychus were secondarily flightless (Czerkas, 2002).

  10. Consider section 3.10 from this reference:

    Flying Oviraptors may have evolved from flying Scansoriopterygids

  11. Jeholopterus skull

    Oviraptor skull:

  12. Here is Naish:

    The fact that long remiges have now been documented in oviraptorosaurs, dromaeosaurids and other maniraptorans shows that feathered arms essentially the same as those present in basal birds evolved somewhere round about the base of the oviraptorosaur + paravian clade, and there is no evidence that wing-like arms were present in more basal coelurosaurs, nor in other theropods, or other dinosaurs, or other archosaurs.

    Sawyer et al. (2003b:30) argued that
    the present study raises the possibility that [the]
    “filamentous integumentary appendages” [of
    coelurosaurs] may more closely resemble the
    bristles of the wild turkey beard, and may not
    depict intermediate stages in the evolution of
    and concluded that
    Without more detailed information about the cellular
    and molecular nature of the “filamentous
    integumentary appendages” of non-avian dinosaurs,
    and more information on the presence or
    absence of follicles, it may be premature to assume
    the homology of all these “filamentous integumentary
    appendages” with feathers.

    The discovery that structurally unique "filamentous integumentary appendages" are associated with several different non-avian dinosaurs continues to stimulate the development of models to explain the evolutionary origin of feathers. Taking the phylogenetic relationships of the non-avian dinosaurs into consideration, some models propose that the "filamentous integumentary appendages" represent intermediate stages in the sequential evolution of feathers. Here we present observations on a unique integumentary structure, the bristle of the wild turkey beard, and suggest that this non-feather appendage provides another explanation for some of the "filamentous integumentary appendages." Unlike feathers, beard bristles grow continuously from finger-like outgrows of the integument lacking follicles. We find that these beard bristles, which show simple branching, are hollow, distally, and express the feather-type beta keratins. The significance of these observations to explanations for the evolution of archosaurian integumentary appendages is discussed.

    Also, the use of bipedal coelurosaurian
    outgroups, as in the analysis by Clark et
    al. (2002), may be contributing to a potentially
    misleading topology. Outgroup choice determines
    the polarity of character states, including
    ancestral reconstructions for entire clades (Nixon
    and Carpenter 1993). In this case, using bipedal
    cursors as outgroups may obscure phylogenetic
    signal by wrongly treating characters indicating
    flight loss as plesiomorphy.