Inferring behaviour from ecomorphologies of feathered theropods

[Stephan Pickering <stefanpickering2002@yahoo.com>]

    In 1965, G. van Tets published a still fascinating
study of pelecaniform theropods' social displays,
believing they could be used, in part, to determine
phylogenetic relationships with homologies. He
started, first, with gaping (so many restorations show
theropods walking about, mouths hanging open
[interesting for children who, in a museum or in a toy
store, will snarl back], when what is being shown is
gape or threat  display). This behaviour is
recognition signalling between individuals, one
usually brooding over eggs, who then moves the head 
with jaws open. The gape display is, van Tets
theorized, derived from threat display.
    Although shirked by systematicists of pre-K/T
dinosaur clades, even now behavioural patterns (we
might even call them "nodes", synapomorphies, etc.)
are avoided by dinosaur scholars due to the questions
of homoplasy, high degree of adaptational change of
dinosaurs since the end-Cretaceous, etc. In short:
behaviour is considered a nebulous area, even though
the morphologies of all dinosaurs can, and have,
determine behaviour. Behaviour among theropods is not
necessarily convergence, and these behaviours can, as
it were, be "mapped" onto a cladistic tree. By looking
at a feathered dinosaur's skeleton, and knowing the
biozone it inhabited (lakeside, seashore area,
woodlands, etc.), its probable diet, possible
coloniality strategies, I believe it possible one can
infer possible behaviour, if one can, e.g., use a
computer generated image of the animal. One could
carefully manipulate the image, testing the actual
physical limitations of head and body movement.It was
done rather well with some of the animals designed by
FrameStore for the WALKING WITH DINOSAURS series,
e.g., how pterosaurs may have walked, and has
demonstrated the neck movement/posture of  sauropods.
    From this, I believe we can outline possible
behaviour systems of pre-K/T feathered dinosaurs.
    1) nest-material presentation between individuals
    2) bowing
    3) hopping (Eddy van Dijk in 2001, and Mike Raath
in his 1977 dissertation, have proposed some dinosaurs
were saltatorial)
    4) arching of neck before hopping
    5) female/male advertising: pointing to sky,
alternate waving of arms (slow or rapid fluttering),
throwback and darting
    6) vocalisation during female/male advertising
    7) female/male rump patch flashing
    8) female/male advertising through wing
positioning (how primary is situated relative to
secondary feathers), with wings folded or spread
and/or raised
    9) kinking of throat
   10) wagging of head
   11) gaping
   12) positioning of dinosaur's head during gaping:
upwards stretched neck, head swung back or forward
   13) gaping repeated
   14) gape vocalization, and similarity/dissimilarity
of vocals of sexes
   15) pointing presence or absence
   16) body twisted or not prior to take-off
   17) pointing to sky prior to take-off
   18) primary feathers folded behind secondary
feathers prior to take-off
   19) snout pointed forward or upward prior to
take-off
   20) median crest-raising prior to take-off
   21) head expanded and snout raised prior to
take-off
   22) head raised prior to take-off
   23) vocalising prior to take-off
   24) snout pointed downwards after landing
   25) head biting after landing 
   26) back-pawing after landing
   27) calls during display after landing
   28) gargle-threat 
   29) both animals wing-bowing
   30) both individuals quiver-bowing
   31) both individuals wagging heads
   32) snout pointed up and away
   33) stepping used
   34) locomotion of animal: irregular gait with
assistance from wings; high stepping gait; waddling
with wings spread out for balance
   35) threat behaviour: biting ("pecking"),
screeching; pointing or wagging of snouts; moving
toward intruder; snapping and waving of open jaws; the
s-shaped neck expanded with snout open, and head
thrown forward; constant darting of head with head
shaking and gargling vocalisations
   36) nest-worrying
   37) water begging
   Some of these, to be sure, would be guesses, some
could be determined by having a physical model of the
skeleton on one's desk so that one could (like Ray
Harryhausen or Willis O'Brien) actually manipulate the
skeleton. One could see how far a head and jaws could
open and move, judge the possible area and volume of
lungs (= inferring strength of vocals), see the limits
of movement ranges of wings (arms with feathers).






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