Chinlechelys tenertesta
- New Turtle: Chinlechelys tenertesta
- Name Means: Delicately-shelled Chinle Turtle
- Relations: Basal Turtle
- Holotype: NMMNH P-16697, partial skeleton including pieces of carapace, plastron, neck spine, etc.
- Location: New Mexico, U.S.A.
- Age: Late Triassic, ~205,000,000 years ago
- Info: The fragments that make up the holotype of Chinlechelys include one and one-half dorsal vertebrae that are fused to a thin bit of shell in a distinctively turtle-like manner. Other pieces include a chunk of the plastron, or lower shell, and a piece from the rear of the carapace (upper shell) with bits of rib on the underside. Two spikes of armor were found that may have protected the animal’s neck—similar spikes adorned the necks of more completely known Triassic turtles like the European Proganochelys.
The more impressive bits of Chinlechelys on display at the NMMNHS.- Joyce et al. consider Chinlechelys to be something of a “turtle-in-progress.” Its shell is extremely thin (1 to 3mm thick) and, unlike all other turtles, its ribs do not appear to be tightly fused to its carapace. This fossil could help resolve a long-standing controversy in turtle evolution—did the turtle shell evolve as the ribs widened and fused together into a dome-like shell, or did rows of armor plating in the skin expand until they fused together and integrated with the ribs and vertebrae for support? According to its describers, the thin shell and loosely integrated ribs of Chinlechelys provide compelling evidence for the latter scenario.
- Reference: Joyce, W. G., Lucas, S. G., Scheyer, T. M., Heckert, A. B., and Hunt, A. P., 2008. A thin-shelled reptile from the Late Triassic of North America and the origin of the turtle shell Proceedings of the Royal Society B Published online (FirstCite). DOI: 10.1098/rspb.2008.1196
- Elsewhere on the Web:
—Matt Celeskey.
File under: Reptiles, Triassic.
Comments on record: (1)
Pachyrhinosaurus lakustai
- New Dinosaur: Pachyrhinosaurus lakustai
- Name Means: Lakusta’s Thick-nosed reptile.
(Al Lakusta discovered the Pipestone Creek Bonebed where the fossils of this dinosaur were found.)
- Relations: Ceratopsian
- Location: Alberta, Canada
- Age: Late Cretaceous, ~73,000,000 years ago
- Length: 6 meters, ~20 feet
- Weight: 1800 kilograms, ~2 tons
- Info: Pachyrhinosaurus lakustai is known from fossils first discovered more than 30 years ago in a densely packed bonebed in Alberta, Canada. Like the previously known species of Pachyrhinosaurus, P. canadensis, this new species had a thickened mass of bone (or boss) atop its nose as an adult. Unlike P. canadensis, the bosses of P. lakustai are present only in adults—juveniles of the new species were found to have horns like those of other ceratopsians. P. lakustai also differs from P. canadensis in smaller overall size and details of the ornamental spikes and bumps on its frill, according to the summary page of the newly released monograph describing this species.
- Reference: Currie, P. J., Langston, Jr., W., Tanke, D. H., 2008. A New Horned Dinosaur from an Upper Cretaceous Bone Bed in Alberta. NRC Press. 152pp. ISBN-13 9780660198194.
- Web coverage:
- Update (10/3/08): Lawrence Witmer and Ryan Ridgely have made their work on the brain cavity and inner ear of Pachyrhinosaurus lakustai available online. From their “common language summary”:
Indeed, the most remarkable aspect of the brain structure of Pachyrhinosaurus is how small and primitive it must have been…Despite the cranial ornaments suggestive of perhaps elaborate behavioral displays and other evidence suggesting herding behavior or even migration, the behaviors of Pachyrhinosaurus were probably relatively simple, stereotyped, and instinctual.
—Matt Celeskey.
File under: Cretaceous, Dinosaurs.
Comments on record: (0)
Aerosteon riocoloradensis
- New Dinosaur: Aerosteon riocoloradensis
- Name Means: Air bones from the Rio Colorado
- Relations: Basal (allosauroid?) tetanuran theropod
- Size: 9 meters/30 feet long
- Location: Cañadon Amarillo, Argentina
- Age: Late Cretaceous, ~84,000,000 years ago
- Info:
Key to the pneumatic features reported in Aerosteon riocoloradensis
from Sereno et al. 2008. See here for detailed caption.
The fossilized bones of Aerosteon are extensively pneumatized— that is, riddled with hollow spaces. In life, some of these spaces would have housed air sacs that helped maintain a steady flow of air through the dinosaur’s rigid lungs. Modern birds have inherited this type of respiratory system from their dinosaurian ancestors, who may have developed this distinctive aerated anatomy in order to breathe more efficiently, or lighten their load and keep balance while running on two legs, or as a built-in air-cooling system to keep from overheating. The extreme degree of pneumatization preserved in a relatively primitive theropod like Aerosteon helps researchers pinpoint when specific features of the avian respiratory system first evolved.
- Reference: Sereno, P. C., Martinez, R. N., Wilson, J. A., Varricchio, D. J., Alcober, O. A., Larsson, H. C. E., 2008. Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina PLoS ONE 3(9): e3303. doi10.1371/journal.pone.0003303.
- Web coverage:
- Update 10/6: Matt Wedel reviews the current state of research on dinosaur pneumaticity and raises some criticisms of Sereno et al.’s paper describing Aerosteon in two posts over on SV-POW.
—Matt Celeskey.
File under: Cretaceous, Dinosaurs.
Comments on record: (1)
Critters with great big claws on their fingers
You could almost say, “Critters whose great big claws are their fingers”:
—Matt Celeskey.
File under: Cretaceous, Dinosaurs, Mammals, Neogene.
Comments on record: (0)
Embracing the Inner Fish
In this case, mine appears to be a Triassic coelacanth:
This was the scene at The Day Job a couple of weeks back, as we unpacked a sculpture for the newly-opened Triassic exhibit. I happened to be wearing the right shirt for the occasion, and my boss David snapped this picture. The piece I’m holding is a fantastic restoration of the freshwater coelacanth, Chinlea sorenseni, about to snap up a school of Synorichthyes. The fish were sculpted by the talented Gary Staab of Staab Studios for the exhibit.
And here’s how the sculpture looks on display, beneath a cast of an fossil Chinlea skull and some Triassic coelacanth bits from New Mexico. The panel is sandwiched between a petrified lungfish burrow and the reconstructed leaves of the enigmatic plant Sanmiguelia. A reflection from the fishtank of Kirby, a living African lungfish, can be seen in the window:
—Matt Celeskey.
File under: Bony Fish, The Day Job, Triassic.
Comments on record: (2)
