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German troodontid tracks



From: Ben Creisler
bh480@scn.org


A few weeks back, there was a DML posting about a dinosaur track symposium
at Obernkirchen, Germany scheduled for April 14-17, 2011:
http://dml.cmnh.org/2011Feb/msg00209.html
with a link to http://www.dinosaurtrack.de/
The text and photos on the site discuss troodontid tracks.

My posting yesterday about some recent international dinosaur stories could
use a clarification about the tracks from Obernkirchen discussed in a video
clip. (The German television program was first broadcast in May 2010--the
showing earlier this week was a rebroadcast.) What might not be immediately
clear is that the two-toed tracks are from troodontids, not dromaeosaurid
"raptors."

When the two-toed tracks were first discovered in 2008, they were
attributed in the media to a Velociraptor-type dinosaur. See the posting to
the DML in September 2008: http://dml.cmnh.org/2008Sep/msg00144.html.
See also pictures and videos of the track site, which depict a model of a
"raptor" standing in the tracks.
http://www.obernkirchen-info.de/spuren.htm


However, the 20 cm (8 in) long tracks were later identified as troodontid.
See the SVP meeting abstracts from 2009:

VELOCIRAPTOR?S SISTERS: FIRST REPORT OF TROODONTID TRACKS FROM THE LOWER
CRETACEOUS OF NORTHERN GERMANY
VAN DER LUBBE, Torsten, Niedersächsisches Landesmuseum Hannover, Hannover, 
Germany; RICHTER, Annette, Niedersächsisches Landesmuseum Hannover,
Hannover, 
Germany; BÖHME, Annina, Niedersächsisches Landesmuseum Hannover, Hannover, 
Germany 
Within a spectacular new dinoturbated tracksite from the Lower Cretaceous
(Berriasian, ?German Wealden?), didactyl footprints have been discovered in
summer 2008. The occurrence of these app. 20 cm long tracks on a surface
from the Obernkirchen Sandstone Quarries (Obernkirchener Sandsteinbrüche)
is a novum for Europe. Hundreds of tridactyl theropod tracks led to the
popular name ?chicken yard?, an area covering more than 400 m². The
didactyl tracks can clearly be assigned to the Troodontidae due to
morphological and morphometrical characters: the angle between digits III
and IV is always greater than 20°, and digit IV is noticeably shorter than
III (n = 60). Thus, these tracks represent the first record of footprints
attributable to that clade of theropods worldwide. Many of the 60
individual footprints, arranged in 11 trackways, are preserved excellently,
showing well defined impressions of the claws, digital- and metatarsal
pads. The unexpected discovery of an extremely narrow ?standing position
track? (left and right foot directly aside) offers interesting insight into
troodontid posture. No trace of the specialized claw of digit II is
detectable in any of the tracks (n = 60). Two groups of trackways show a
parallel orientation. One is composed of three trackways (W? direction),
the other of four (SW? direction). In the latter group, two trackways
exhibit the same type of preservation and show equal pace- and
stride-lengths. These characteristics strongly suggest a simultaneous
movement of at least these two individuals and thus some degree of social
behavior. In contrast, one trackway within the first, westerly directed
group displays clear preservational differences from the others, which
means that this animal crossed the Cretaceous lagoon at another time. This
particular trackway consists of 12 consecutive footprints, representing the
longest didactyl trackway on the ?chicken yard? surface. The neighboring
quarry area is still covered by app. 7 m of sandstone, so that the ongoing
quarry work will offer the opportunity to continuously add data within the
next years.

-----
As far as I can determine with a quick, non-exhaustive search of the
literature, these tracks have not been formally named yet. Have they been
described officially in a technical paper?

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