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Photogrammetric analysis of large dinosaur tracks at Lark Quarry
Re: Romilio & Salisbury on photogrammetric analysis of large dinosaur tracks at
Lark Quarry, Queensland. (Cretaceous Reseach, 51: 186-207; 2014).
They still haven't got it right, even after 3 years and 3 papers. For the
100th time, this is what Mary Wade and I said in 1984:
At Lark Quarry there are >150 trackways of small bipedal dinosaurs; all those
small animals were apparently running in the same direction at or about the
same time (preservation of their tracks is pretty uniform throughout). We
regarded those tracks as evidence of a stampede. There are also tracks of a
few other, bigger and slower-moving animals, but these traversed the site in
various directions *before* the running animals did so (those earlier tracks
differ in preservation; some show effects of long-term erosion, others are
overtrodden by the running animals). These other tracks are *not* evidence of
a dinosaur stampede, though they might (or might not) help to explain the
occurrence of a stampede, depending on how you interpret them.
What does it all mean? What could have caused >150 dinosaurs to bolt for the
hills? Mary and I had two options:
(1) Just leave it all dangling and unanswered. Tell the world it's
inexplicable and wait for all the crackpot/creation science/crop
circle/cryptozoology/cosmic conspiracy (etc.)theorists to shift their attention
from Loch Ness to Lark Quarry. No thank you. It's hard enough already,
without busloads of latter-day loonies crawling over the site in search of
astronomical alignments and portents of doom.
(2) Use all the information we had (NB *all* of it), however incomplete, to
construct a plausible scenario that might explain the occurrence of a stampede
and the peculiarities of the Lark Quarry track assemblage. Our scenario was
clearly packaged and labelled as speculation and it played out at some unknown
site nearby and downstream (to the SW) of Lark Quarry - NOT at Lark Quarry
itself. It was an optional extra, not evidence of a dinosaurian stampede.
So, Mary an
nents: (1) description and interpretation of Lark Quarry; and (2) conjecture
about background events that might explain the pattern of trackways at Lark
Quarry - though such events must have taken place elsewhere, NOT at Lark Quarry.
Yet, once again, Romilio & Salisbury have rolled the two components together
indiscriminately, mixing the speculations (2) into the evidence at Lark Quarry
(1) and emerging with their own semi-fictional stories - which they have then
attributed to me and to my late co-author Mary Wade. Here's an example (2014,
p. 187), where I've indicated which parts of their story are actually from Lark
Quarry [A] and which aren't [B].
"The complex track patterns present at Lark Quarry [A] had also led to
speculation that the small-bodied dinosaurian trackmakers may have interacted
or responded in some way [B] to the presence of a much larger one (Thulborn and
Wade, 1984). In the context of this interpretation [is that A? or is it B? or
is it both?], the largest Lark Quarry trackmaker was considered to have
‘approached’ the smaller trackmakers [B] (Thulborn and Wade, 1984: 413, 443,
445, 455) - even though the trackway data [A] indicates the large-bodied
trackmaker 'was heading in the opposite direction' [A] (Thulborn, 2013: 3) -
and in some way 'triggered' a stampede [B] (Thulborn and Wade, 1984: 413, 443)."
Just in case you lost track, that's a narrative constructed from bits of A + B
+ A?(and/or B?) + B + A + A + B.
Mary and I *never* suggested that such events occurred at Lark Quarry, but
anyone reading that Romilio-Salisbury account is likely to believe that we did.
All three of the Romilio & Salisbury papers on Lark Quarry (Cretaceous
Research 2011, 2014; JVP 2012, with co-author RT Tucker) involve similar
ambiguities and straw men, but I don't propose to waste any more time trying to
sort out the mess. For the moment I'll just reproduce the final paragraph from
my 2013 paper in Alcheringa ("Lark Quarry revisited...") and then - for
comparison - tack on a couple of extract
"The existing interpretation of the Lark Quarry site (Thulborn & Wade, 1984) is
not exempt from criticism. Scientific understanding of dinosaur tracks has
advanced very considerably since the 1980s, and there are certainly
shortcomings and errors in the existing accounts of the site. Some of the small
footprints shown in the overall plan of the tracksite (Thulborn & Wade 1984,
pl. 17) are misplaced, and the attempt to discern size/age classes among the
numerous trackmakers (p. 438) was, in retrospect, a case of reading far too
much significance into fragmentary evidence. Even so, the identity of the large
track-maker, whether theropod or ornithopod, is of no great importance to the
overall interpretation of the site. The presence of a theropod might help to
explain the occurrence of a stampede, by inviting some speculation (clearly
labelled as speculation), while the presence of an ornithopod might not. But in
either case, the evidence of a stampede
remains unaltered, and the identity of the large track-maker is a separate
matter of secondary interest. Consequently, it has not been my intention here
to argue one way or the other about of the identity of that large track-maker
at Lark Quarry. The intention has been to restate the existing interpretation
of Lark Quarry (which seems to have been grievously misrepresented) and to
explain that Romilio & Salisbury (2011) have provided no legitimate reason to
question that interpretation."
That's the concluding paragraph from my 2013 paper in Alcheringa ("Lark Quarry
revisited..."). Bear it in mind as you sample the following remarks from
Romilio & Salisbury's latest article (2014, Cretaceous Research) on the Lark
Quarry dinosaur tracks.
1)"Thulborn (2013) instead maintained that the original identification of these
[largest] tracks and the overall interpretation of the site proposed by
Thulborn and Wade (1984) were correct." (2014: 188)
No. I said (2013) that the original interpretation (1984) wasn't perfect.
But since the only alternative (Romilio & Salisbury 2011) wasn't acceptable,
the original interpretation (1984) is the only one we've got, at least for the
time being. I haven't said that the original interpretation is correct.
2) "In a recent description of Lark Quarry, Thulborn (2013: 1) maintained there
was no 'substantial flaw in the existing [i.e. Thulborn and Wade's (1984)]
interpretation of the Lark Quarry dinosaur tracks', and continued speculation
that the 'presence of a theropod [the cf. Iguanodontipus trackmaker] might help
explain [the movement of the smaller dinosaurian trackmakers]'. The results of
our study suggests otherwise." (2014: 205).
No. It wasn't a description of Lark Quarry: it was a critique of methods
used to identify one track-maker at the site. And no, it didn't continue
(extend?) speculation about the presence of a theropod track-maker. It said
there are two possibilities, one of which (theropod) might be more helpful than
the other (orni
e occurrence of a stampede. And it added that the question really doesn't
matter anyway ["in either case, the evidence of a stampede remains unaltered"],
so I won't waste everyone's time by arguing about it.
Anthony Martin's newly-published book 'Dinosaurs Without Bones', chapter 3
('The Mystery of Lark Quarry') makes the same point: "I'll further state,
somewhat impudently, that in the 'stampede' hypothesis, the identity of the big
trackmaker doesn't matter."
Yet, somehow, Romilio & Salisbury seem to have persuaded themselves that it
really does matter, and they've just filled another 22 pages trying to convince
everyone else. The stated aim of their study (2014: 188) was "to document the
3D morphology of the tracks of the largest Lark Quarry trackmaker, along with
associated surface structures (e.g. displacement rims), using objective methods
... " and to determine whether or not "the largest dinosaurian Lark Quarry
tracks were ... formed synchronously (or near-synchronously) with tracks formed
by the small-bodied dinosaurs...". All very interesting, but none of this
(footprint morphology and the chronology of events at Lark Quarry) has any
bearing on the evidence for a dinosaurian stampede.
Yes, their latest paper also involves those remarkable "swimming dinosaurs"
(JVP 2012) and the fluctuating water-levels that so mystified Steve Poropat
(DML July 10th; 'Re: Australian Lark Quarry dinosaur stampede trigger
scenario'; via Tim Williams), but I'll try to clarify those matters elsewhere.