Paleoecology of the Arlington Archosaur Site, Texas.

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Paleoecology of the Arlington Archosaur Site,
Texas.

• Derek J. Main
• University of Texas

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Arlington, Texas!
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Dallas Cowboys Football!!
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Dinosaurs in Arlington!!
The Arlington Archosaur Site!
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Arlington Archosaur Site
Discovered in 2003 by Art Sahlstein, Phil
Kirchhoff and Bill Walker.
Site located in north Arlington, Texas.
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What are Archosaurs?

• Archosaurs the ruling reptiles of the Mesozoic
  Era Dinosaurs, pterosaurs
• and crocodiles.

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The Arlington Archosaur Site
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Arlington Archosaur Site
Dig began after 6 yr wait!
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UTA - Dinosaurs Class Excavations
UTA dinosaurs students in the field, 2009.
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College students like to dig!
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Arlington Archosaur Site BIG Digs!
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Arlington, Texas Geology Woodbine Formation
Marine Cretaceous
Terrestrial Cretaceous
W O O D B I N E
Cretaceous of Dallas- Ft Worth
Deltas Dinosaurs
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Woodbine Formation
Mapped and named by R. T. Hill in 1905 for the
small town of Woodbine in north Texas. A
Mid-Cretaceous (100 mya) unit, coastal deposits
deltas.
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Deltaic Sequences
Woodbine Formation Coarsening upwards
sequence
Upper Delta Plain sand
Paleosol
Upper Delta Plain shale
Paleosol
Lower Delta Plain sands
Delta Front sands
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Delta Plains Distributary Channels
Delta channel avulsion bifurcation
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Arlington Archosaur Site Deltas
Arena croc sites
Coastal-delta facies fossils on hill
AAS Hillside fossil sites
Mr. Croc Crocorama sites
Theropod site
Dino-quarry
lungfish site
Trace fossil site
Shark fish site
Ripples
Near shore marine facies fossils in field
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Arlington Archosaur SitePaleoenvironments
Skolithos facies horizontal burrows
Sedimentary structures, trace fossils teeth!
Ripples
Skolithos facies
Flow
Fish Pycnodont
Sharks Cretodus
Rhizocorallium
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Delta Plain Peat Trees
Fossil log 3.5m (gt9 ft)!
Phil Scoggins and the log he found
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Delta Plain Facies Avulsion belts

• Farrell (2000) recognized 5 delta plain -avulsion
  facies
• 1) Sand Facies (cross laminated cross beds)
• 2) Heterolithic Facies rythmites
• 3) Mudball clast facies mudballs and gastropods
• 4) Mud Paleosol Facies
• 5) Peat Facies

Woodbine Formation Arlington Archosaur Site
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Arlington Archosaur SitePaleoenvironments Peat
bog Logs
Peat Facies, (Farrell, 2000)
logs organics
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Delta Plain Facies Paleosols
- Delta Plain composed of fine sand/silt with
coal shale beds with distinct paleosols.
Paleosol 2
Paleosol structures roots
Sulphuric staining

• Paleosol Histic Gleysol

Mud Paleosol Facies, (Farrell, 2000)
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Delta Plain Sand Facies Rythmites
Heterolithic Facies (Farrell 2000) Rythmites
sand lamninae in mud.
Sand Facies (Farrell, 2000)
Sand lenses
Woodbine Formation outcrops Arlington Archosaur
Site
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Delta PlainPaleoenvironments Paleosols Coal
Woodbine Formation
Paleosol
Paleosols
Coal beds
burrow
Heterolithic muds
Lungfish burrow
Sand lense
Heterolithic muds (rythmites)
Coal
Paleosol Mud Facies
Paleosol
Calcrete nodules
Roots
Woodbine Formation Arlington Archosaur Site
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Arlington Archosaur SitePaleoenvironments
Mangroves
Mangroves
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AAS DinosaursOrnithopods
Ornithopoda bird foot term 1st used by Marsh
(1881) to name bipedal, unarmored herbivorous
dinosaurs, some of which had complex
dentitions (hadrosaurs). They lived from the
Lower Jurassic to Upper Cretaceous (145-65mya)
and had a global distribution.
3 toed bird foot track
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Ornithopod cladogram
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Iguanodon Iguana tooth

• The 1st Iguanodon tooth.
• Mr. and Mrs. Mantell

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Iguanodon
Famous Iguanodon thumb spike.
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Hadrosaur Classification
Hadrosaurs are subdivided into 2 groups
Hadrosaurines (non-crested)
Lambeosaurines (crested)
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Charonosaurus
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Hadrosaur nesting colonies
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Texas Ornithopod dinos
Protohadros- Discovered by Gary Byrd in Flower
Mound in 1992. Found skull along roadside
construction. Named Protohadros by SMU student
Jason Head (1998). Oldest hadrosaur in North
America. Name means primitive hadrosaur.
Primitive hadrosaur ?
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Protohadros fossils
Fossils at SMUs Shuler Museum of Paleontology,
Dallas.
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Dinosaur Vertebrae
Cervical vertebrae (neck)
Dorsal vertebrae (back)
Caudal vertebrae (tail)
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Dinosaur back (dorsal) vertebrae
Ornithopod
Amphicoelus concave to the
posterior.
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Dinosaur back (dorsal) vertebrae
Ornithopod
Rounded centra, typical of Dorsal vertebra.
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Dinosaur caudal (tail) vertebrae
Ornithopod
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Iguanodont Scapulae
Iguanodon
Broad Sacpula
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Hadrosaurs are hip!
Dinosaurs divided into two groups by H.G. Seeley
in 1880s
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Dinosaur Pelvis (hip) Ischium
Pubic peduncle
Acetabulum
Ilial peduncle
Ornithopod
Bill Walker
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Iguanodonts have a laterally compressed, blade
like pre-pubic process
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So what do we have?..
Post cranial hadro-dont skeleton!
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Ornithopod fossils
So what do we have?..
We need this!
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The Arlington T-rex
New tyrannosaur?
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Edmontosaurus attacked!
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Arlington Archosaur Site
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New Crocodile
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Crocodiles
Woodbinesuchus
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Coprolites Dino-poop!
Dino-poop can be used to study ancient
ecosystem dynamics, the animals present and what
they ate..
Dino- poop?
Fish- poop
Croc- poop
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Arlington Archosaur Site
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Discovery Channel
Watch for the Arlington Archosaur Site on
the Discovery Channel special Prehistoric
America
Spring 2010
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Arlington Archosaur Site
Want to go on a dino-dig? Ask Derek
maindinos_at_msn.com