Paleontology question: In reading up on prehistoric synapsids and mammals I've noticed a great deal of them have 'odon' at the end of their names: e.g. smilodon, hyaenodon, dimetrodon, sphenacodon, mastodon, etc. I've gathered that the 'odon' stands for tooth -- but I'm curious why so many mammals and, uh, reptiles-that-evolved-into-mammals are named for their teeth, while not many (if any?) true dinosaurs are. Is there any particular reason for that naming convention?
(crownedrose here to answer). It all comes down to who named the animal, when it was discovered, how much of it they had to go on, and whether they stuck to the general dinosaur ending. Some dinosaurs, like Iguanodon, do have the ending -odon because they had many teeth to go off of when it was found. When dinosaurs were first discovered, they were thought to be these massive and “terrible lizards”, which is exactly what dinosaur means. Though calling them a “terrible lizard” is incorrect as dinosaurs are not lizards. Though the suffix -saurus doesn’t apply to all dinosaurs — as everyone knows — most dinosaurs are named “[something] lizard” in translation, which is usually the go-to when naming a dinosaur, as I stated above.
You have many others that do not share the -saurus ending, like the well known Triceratops (which means “three-horned face), or Deinonychus (“terrible claw”). Why doesn’t every dinosaur end with -saurus then? There’s something called the Dinosaur Renaissance, which was the turning point in time where dinosaurs went from these cold-blooded lizards which drudged along the Earth, to the way we see them more today. This didn’t create all names to be changed of course, but with some dinosaurs, this did occur. Deinonychus is a great example of name-changing. When it was first discovered in the 1930’s by Barnum Brown, it’s original name was Daptosaurus agilis, but with Brown never finishing his work, the name was changed later on in the 60’s when a palaeontologist named John Ostrom discovered his own remains of Deinonychus (going off a complete foot, which was the origin of the new/official name), and also reviewed the issues with Brown’s work (bones from multiple dinosaurs were accidentally identified as one specimen). There have been many cases of dinosaurs being misclassified (the Brontosaurus/Apatosaurus case is a famous one). Though to get back to the main point, most are named because of their superorder (Dinosauria), and the help of Ostrom and other palaeontologists which revolutionised the way we see dinosaurs now has also been in affect of how some are named in more recent times.
Electrical response overlaid on the inner aortic wall. (Credit: Jiangyu Li, UW)
The heart’s inner workings are mysterious, perhaps even more so with a new finding. Engineers at the University of Washington have discovered an electrical property in arteries not seen before in mammalian tissues.
The researchers found that the wall of the aorta, the largest blood vessel carrying blood from the heart, exhibits ferroelectricity, a response to an electric field known to exist in inorganic and synthetic materials. The findings are being published in an upcoming issue of the journalPhysical Review Letters.
“The result is exciting for scientific reasons,” said lead author Jiangyu Li, a UW associate professor of mechanical engineering. “But it could also have biomedical implications.” A ferroelectric material is an electrically polar molecule with one side positively charged and the other negatively charged, whose polarity can be reversed by applying an electrical field.
Ferroelectricity is common in synthetic materials and used for displays, memory storage, and sensors. (Related research by Li and colleagues seeks to exploit ferroelectric materials for tiny low-power, high-capacity computer memory chips.)
In the new study, Li collaborated with co-author Katherine Zhang at Boston University to explore the phenomenon in biological tissues. The only previous evidence of ferroelectricity in living tissue was reported last year in seashells. Others had looked in mammal tissue, mainly in bones, but found no signs of the property.
The new study shows clear evidence of ferroelectricity in a sample of a pig aorta. Researchers believe the findings would also apply to human tissue.
why did they change the cretaceous-tertiary event to the cretaceous-paleogene event?
(crownedrose here to answer) Fantastic question! It pretty much boils down to the origin of “Tertiary” which was pinned back in the 1700’s by an Italian geologist, Giovanni Ardunio. He had split the Earth’s time into four periods when studying in the Alps: Primitive, Secondary, Tertiary, and the well known Quaternary (the only term to have truly survived/recognised).
When it comes to the term in question, what was once the Tertiary has now been split into the more well known and used terms. You have the Paleogene period (the first in the Cenozoic era), and its three Epochs: Paleocene, Eocene, and Oligocene. Originally the Tertiary was both the Paleogene (aka informal ‘lower Tertiary system’) and Neogene (aka informal ‘upper Tertiary system’) periods, respectively. Because it is not recognised as a formal time unit by the International Commission on Stratigraphy, the change to the Cretaceous-Paleogene (K-Pg) extinction event was imminent.
So when it comes to the change in names, it was all because of the advancement of knowledge, discoveries, and exploration by other geologists and palaeontologists with much more detailed and accurate research from all over the planet. Ardunio’s work (and four names) had only been explored in the Alps where he researched, so when they were applied to other areas outside the Alps, that’s when the terms (Primitive, Secondary, and for the most part - Tertiary) had to be dropped; because - well - everywhere on the planet is not exactly like the Alps! To sum all of this up (it’s ridiculously late where I am so I apologise for the rambling, and hopefully this has all been making sense), the name was changed to be up-to-date with the recognised time units we have now. Most people (including myself), still refer to it as the K-T extinction event, but with time we’ll all probably get used to its new name.
Cosmology is the scientific study of the large scale properties of the Universe as a whole. It endeavors to use the scientific method to understand the origin, evolution and ultimate fate of the entire Universe. Like any field of science, cosmology involves the formation of theories or hypotheses about the universe which make specific predictions for phenomena that can be tested with observations. Depending on the outcome of the observations, the theories will need to be abandoned, revised or extended to accommodate the data. The prevailing theory about the origin and evolution of our Universe is the so-called Big Bang theory.
Big Bang Cosmology
The Big Bang Model is a broadly accepted theory for the origin and evolution of our universe. It postulates that 12 to 14 billion
years ago, the portion of the universe we can see today was only a few millimeters across. It has since expanded from this hot
dense state into the vast and much cooler cosmos we currently inhabit. We can see remnants of this hot dense matter as the
now very cold cosmic microwave background radiation which still pervades the universe and is visible to microwave detectors
as a uniform glow across the entire sky.
Foundations of The Big Bang Model
The Big Bang Model rests on two theoretical pillars:
The first key idea dates to 1916 when Einstein developed his General Theory of Relativity which he proposed as a new theory
of gravity. His theory generalizes Isaac Newton’s original theory of gravity, c. 1680, in that it is supposed to be valid for bodies
in motion as well as bodies at rest. Newton’s gravity is only valid for bodies at rest or moving very slowly compared to the
speed of light (usually not too restrictive an assumption!). A key concept of General Relativity is that gravity is no longer
described by a gravitational “field” but rather it is supposed to be a distortion of space and time itself. Physicist John Wheeler
put it well when he said “Matter tells space how to curve, and space tells matter how to move.” Originally, the theory was able
to account for peculiarities in the orbit of Mercury and the bending of light by the Sun, both unexplained in Isaac Newton’s
theory of gravity. In recent years, the theory has passed a series of rigorous tests.
The Cosmological Principle
After the introduction of General Relativity a number of scientists, including Einstein, tried to apply the new gravitational
dynamics to the universe as a whole. At the time this required an assumption about how the matter in the universe was
distributed. The simplest assumption to make is that if you viewed the contents of the universe with sufficiently poor vision, it
would appear roughly the same everywhere and in every direction. That is, the matter in the universe is homogeneous and
isotropic when averaged over very large scales. This is called the Cosmological Principle. This assumption is being tested
continuously as we actually observe the distribution of galaxies on ever larger scales. The accompanying picture shows how
uniform the distribution of measured galaxies is over a 70° swath of the sky. In addition the cosmic microwave background
radiation, the remnant heat from the Big Bang, has a temperature which is highly uniform over the entire sky. This fact strongly
supports the notion that the gas which emitted this radiation long ago was very uniformly distributed.