1517087
Shape shifting dinosaurs: the
cause of premature extinction -
Jack Horner 2011
- Fascination with dinosaurs?
- big
- different
- Morphologicaly
- Used to define different species
- Limitations
- Museums
- Bones precious
- Barrier to cutting open bones
- Barrier to cutting open bones
- Ego
- Find the biggest and best dinosaur possible
- New species by size and morphology
- New species by size and morphology
- Want to name a new dinosaur
- Origonal name sticks, second name gets thrown out
- Torosaurus now triceratops
- Anatatitan becomes Edmontosaurus
- Torosaurus now triceratops
- Origonal name sticks, second name gets thrown out
- Find the biggest and best dinosaur possible
- Bones precious
- Museums
- Limitations
- Used to define different species
- Morphologicaly
- Extinct
- big
- 1970
- Where are all the juveniles?
- Assumed that juveniles would be easily identified
- Anything that looked a little different got named as a new dinosaur
- Anything that looked a little different got named as a new dinosaur
- Assumed that juveniles would be easily identified
- Where are all the juveniles?
- 1975
- Dr. Peter Dodson - University of Pennsylvania
- Growth in dinosaurs is more like chicken and less like reptiles
- Allometric (relative) Cranial (skull) Ontogeny (growth)
- Example: Cassowary
- Birds with crests grow to around 80% before the crest starts to grow
- Retention of juvenile characteristic well into ontogeny
- Looks like two different species
- Looks like two different species
- REFERENCE :
- Retention of juvenile characteristic well into ontogeny
- Birds with crests grow to around 80% before the crest starts to grow
- Relative skull growth
- Example: Hypacrosaurus
- If it grew in a linear fashion it would have a crest around half the size of the adlut
- If it grew in a linear fashion it would have a crest around half the size of the adlut
- Example: Cassowary
- Allometric (relative) Cranial (skull) Ontogeny (growth)
- Growth in dinosaurs is more like chicken and less like reptiles
- Dr. Peter Dodson - University of Pennsylvania
- Hell creek formation
- Produces last dinosaurs
- Produces last dinosaurs
- Dinosaur species - Skulls
that change shape during
ontogeny
- Pachycephalosaurs, Stygimoloch and Dracorex
- Cant determine relationship fully by looking at morphology
- Spike on Dracorex are growing, spike on
Stygimoloch are reabsorbing and dome is growing
and Pachycehalsaur dome is solid and spikes are
still reabsorbing
- Easy to hypothesize that this is a growth series but need evidence
- Easy to hypothesize that this is a growth series but need evidence
- Spike on Dracorex are growing, spike on
Stygimoloch are reabsorbing and dome is growing
and Pachycehalsaur dome is solid and spikes are
still reabsorbing
- Cant determine relationship fully by looking at morphology
- Triceratops
- Horner and Goowdin 2006 - Major cranial changes during
triceratops ontogeny :
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1635501/
- Juveniles grow horns grow backwards and then start to
grow forwards and the triangular spikes along the frill as
juviniles flatten out when they are older
- Cut open the skulls and found degree of sponginess relative to age. Smallest skull
is spongy, intermediate was spongy however largest one is spongy also.
- Torosaurus - 3m long skull looks like triceratops but has mature bone
- Has holes in its frill.
- John Scannella 2010
- 5 questions for John Scannella
http://www.britannica.com/blogs/2010/09/torosaurus-is-triceratops-5-questions-for-paleontologist-john-scannella/
- Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae:
Chasmosaurinae): Synonymy Through Ontogeny
http://www.bioone.org/doi/abs/10.1080/02724634.2010.483632
- Hole starting to form in
triceratops and shows as
open in Torosaurus. Also
found transitional skulls
- ‘Nedoceratops’: An Example of a Transitional Morphology 2010 -
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0028705
- ‘Nedoceratops’: An Example of a Transitional Morphology 2010 -
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0028705
- 5 questions for John Scannella
http://www.britannica.com/blogs/2010/09/torosaurus-is-triceratops-5-questions-for-paleontologist-john-scannella/
- John Scannella 2010
- No juvenile Torosaurus found to date
- Has holes in its frill.
- Torosaurus - 3m long skull looks like triceratops but has mature bone
- Juveniles grow horns grow backwards and then start to
grow forwards and the triangular spikes along the frill as
juviniles flatten out when they are older
- Horner and Goowdin 2006 - Major cranial changes during
triceratops ontogeny :
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1635501/
- Anatatitan is a juvenile Edmontasaurus
- Cranial Growth and Variation in Edmontosaurs (Dinosauria: Hadrosauridae): Implications for Latest
Cretaceous Megaherbivore Diversity in North
Americahttp://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0025186
- Cranial Growth and Variation in Edmontosaurs (Dinosauria: Hadrosauridae): Implications for Latest
Cretaceous Megaherbivore Diversity in North
Americahttp://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0025186
- T-rex and nanotyranus
- Nano had 17 teeth has juvenlie bone, tyrannosaurus
had 12 and more mature bone
- Less teeth as they get older
- Dinosaur Census Reveals Abundant Tyrannosaurus and Rare Ontogenetic Stages in the Upper
Cretaceous Hell Creek Formation (Maastrichtian), Montana,
USAhttp://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0016574
- Dinosaur Census Reveals Abundant Tyrannosaurus and Rare Ontogenetic Stages in the Upper
Cretaceous Hell Creek Formation (Maastrichtian), Montana,
USAhttp://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0016574
- Less teeth as they get older
- Nano had 17 teeth has juvenlie bone, tyrannosaurus
had 12 and more mature bone
- Pachycephalosaurs, Stygimoloch and Dracorex
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