Instructor Assigned Paper 1 – Jan 19
Keenan and Engel, 2017, Early diagenesis and recrystallization of bone: Geochimica et Cosmochimica Acta, v. 196, p. 209-223.
What’s it about?
In order to have the science of vertebrate paleontology, we have to have the fossilization of bones. The authors use experimental methods to examine what happens early in the process of fossilization and understand the role of bacteria in the preservation of bone. Continue reading
Friday Headlines, September 2, 2016
THE LATEST IN THE GEOSCIENCES
Earth’s Oldest Fossils
First Stars Are Younger than We Thought
Little Bitty Pterosaur Continue reading
Amniotes are important. You are an amniote (I promise). Birds are amniotes. Turtles are amniotes. Crocodiles are amniotes. Dinosaurs were amniotes. Dogs and cats are amniotes. Lizards are amniotes.
But amphibians (like the spring peepers that have been so noisy of late) are not amniotes. Fishes aren’t amniotes either. Continue reading
In biology and paleontology, species is everything. It’s a point of pride to have named a new species, just like I feel about naming Fractinus palmorem.
In your middle-school science class, you probably learned that a species is defined as organisms that can reproduce, yielding living and fertile offspring, and that do so naturally. This is the biological species concept. It works great, but for fossils, this idea doesn’t work so well. We can’t observe behavior or reproductive success in the fossil record.
Though we have this strict definition, for practical purposes we recognize different species because members of a species look similar to each other. With fossils, comparing overall ‘looks’ or morphology. Using this method, we can consider fossil species as morphological species. Continue reading
One of the distinguishing features of vertebrates is the presence of bones. We learned in an earlier post that not all vertebrates have bones, but if you do find an animal with bones, you can be confident you’re dealing with a vertebrate.
Structure of a bone.
SEER – U.S. National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) Program Public Domain
You see them in everywhere in papers and posts related to paleontology.
Cladograms showing the same relationships in two different ways.
Alexei Kouprianov CC BY-SA 3.0
Cladograms. Little tree-like drawings that show the relationships among different organisms. A cladogram is a hypothesis about the evolutionary relationships among different organisms (A, B, and C in the cladogram above). Another term for evolutionary relationship is phylogeny. Continue reading
A couple of days ago, I wrote a post about what makes vertebrates distinct from other animals. I alluded to the fact that our closest living relatives that aren’t chordates are the echinoderms, sea stars, sea urchins, sea cucumbers, sea lilies and apparently any organism for which the common name begins with ‘sea’ (except for sea horses – those are fish).
Our cousins, the echinoderms.
Tripneustes ventricosus (West Indian Sea Egg-top) and Echinometra viridis (Reef Urchin – bottom).
Nick Hobgood CC BY-SA 3.0
But how do we know this? The answer is in our embryos. Continue reading
One of those things we do as geoscientists is try to figure out if the rocks in one place are the same as the rocks in another place. While it seems a very easy question to ask, it’s not so easy to answer.
This determination of ‘sameness’ is called correlation. But before we can do any correlating, we have to get more specific in our question. Do we want to know if rocks here and there are the same age, or do we want to know if they represent the same environment?
Cartoon showing rock correlation (solid line) and fossil correlation (dashed line) between layers of rock in three different areas.
When I teach my course in Vertebrate Paleontology (see tweets at #UREES270), one of the first questions that arises is what is a vertebrate? What makes a vertebrate distinct from all other forms of life?
One interesting thing about vertebrates is that they don’t all have vertebrae. This one thing that seems like it should be the obvious thing that all vertebrates share, isn’t shared by all (although if you have an animal with vertebrae, it is most definitely a vertebrate!).
To make matters worse, you’d think that a big important group like the Vertebrata (the scientific name for the vertebrates) would get to have its own Phylum, like the mollusks, the cnidaria (jellyfish and kin), and the echinoderms (sea stars and sea urchins and kin), but no. The Vertebrata is relegated to Subphylum status within the Phylum Chordata, which means exactly nothing to most people.
The chordates (members of the Phylum Chordata) are a really interesting group, however. There are some chordates that are not vertebrates, including the lowly sea squirt, and the lancet (Amphioxus). What these chordates have that is shared with all vertebrates (hence grouping them together) is a notochord.
Clavelina moluccensis, the bluebell tunicate
Nick Hobgood CC BY-SA 3.0
Below are the answers to a series of questions asked of me by a friend from way back in high school. His questions were interesting enough, that I thought I’d post the answers here. Other folks might be interested, too.
These answers come off the top of my head. I did not research them, so I might have a few details wrong. But the overall story should be about right.
Could you give me an example of a lineage with an abundant fossil record that stretches over a very long period? Continue reading