What’s for Dinner? Scientists Uncover Purpose behind Helicoprion’s Distinctive Teeth
I bet you thought Johnny Depp had it bad, having scissors instead of hands. Well, imagine having a buzz saw instead of teeth. Or rather, a buzz saw made entirely of teeth. Sounds like a horror movie, doesn’t it?
But what you’re actually imagining is the everyday life of Helicoprion, a prehistoric ratfish who lived 310 million years ago in the late Carboniferous. Oddly enough, the idea of having a circling death-wheel of teeth (or tooth whorl, as scientists call it) is actually nothing new.
The first Helicoprion fossil was described by Russian geologist Alexander Karpinsky in 1899. There were just two problems the discoverer faced: where the tooth whorl was located on the body, and why this 20-foot fish-of-death had a spiral of deadly fish-teeth at all!
In the century since its discovery, scientists had placed Helicoprion’s teeth all over its body— as a spiral jutting off the tip of the nose, as spines protruding from its back, or as a spiral of ever replacing teeth dangling from its lower jaw, among other (sometimes more fanciful than scientific) ideas.
In 2013, thanks to CT scans of well-preserved fossils, it was finally decided that the tooth whorl was located in Helicoprion’s lower jaw, much like the image above.
But how Helicoprion used this built-in toothy yoyo remained a mystery until September 2, 2014, when biologist Jason Ramsay and the team from 2013 published their findings and finally answered the second question.
According to the researchers, Helicoprion ate by biting its prey, rather than suction feeding, as had been previously proposed. Its favorite dishes were probably prehistoric squid, octopus, and their spiral-shelled cousins, the nautilus. This is where a toothy wheel of death comes in handy. By biting down at the right angle, Helicoprion would have been able to pull a prehistoric nautilus out of its shell, into his terrifying carnival ride of teeth, and straight down his throat all with one fluid movement.
I, on the other hand, have problems peeling an orange. And while I enjoy my orange, I’ll ponder my contentment in learning about another prehistoric mystery, solved by science.
If you’d like to learn more, click on the image above or read the original paper.
Submitted by Nick V, Discoverer.
Edited by Carrie K.
Why is it that the further away an object is, the smaller it appears? Obviously the simple answer is perspective; What causes perspective to be something that we perceive in the way that we do? Why is it that there being three spatial dimensions causes us to perceive objects including ourselves in the way that we do? In a universe wherein four spatial dimensions are at play, does perspective cease to exist? In 4D, do objects still appear smaller the farther away they are from the viewer?
Asked by terraf0rm
Answer:Fascinating question! In fact, your question was so awesome that we had two teams of Experts— biology and physics— collaborate to answer.As you alluded to, your question really gets to the heart of what perception is. When we focus both of our eyes on an object, we receive two-dimensional representations of this object on the center each of our retinas. The images are sent through the optic nerve to the occipital lobe, where our genius of a brain calculates the difference in angle between the two images. This difference, or binocular disparity, is responsible for generating our sense of immersion in our three-dimensional environments.When viewing an object that is further away, our angle of vision of that object is much more acute than it would be if it were closer. As Stephen Pinker explains in Mental Imagery and the Third Dimension, published in the Journal of Experimental Psychology, ”an object will subtend a smaller visual angle when it recedes from the viewer”. This smaller visual angle makes the distant object seem smaller in our field of view than a closer object with a larger angle would appear.Hypothetically, four-dimensional human beings would view their world in the same way— by receiving two slightly different images on their three-dimensional retinas. These retinas would grant four-dimensional humans a sense of depth that isn’t accessible to us, with our mere two-dimensional retinas. Their perceptions of the four-dimensional world of space-time would seem as navigable to them as three-dimensional space is to us.Just as a two-dimensional being would not be able to see inside a square that they’re next to, three-dimensional humans cannot see inside a cube that is next to them. Four-dimensional humans would have no such limitation, being able to view all sides and inside of the cube simultaneously. Utilizing the logic that perspective exists in a two-dimensional world just as it does in the three-dimensional one, we think a visual system adapted to four-dimensional vision would also be subject to the same perspective constraints, and four-dimensional objects would also look smaller to an observer with increasing distance.But of course, we mere 3-D humans can’t know for sure. We suppose you’ll have to ask the first 4-dimensional human you meet.Sources:Pinker, Steven. “Mental Imagery and the Third Dimension.” Journal of Experimental Psychology: General 109.3 (1980): 354-71.
Answered by John M., Expert Leader.
Edited by Dylan S.
NASA’s latest and greatest nuclear-powered, laser-shooting Curiosity rover has arrived at its target destination, Mount Sharp, two years after it landed on Mars last August. Its primary scientific objective was to find out whether or not Mars could have supported life as we know it. In its first year of operation, the Curiosity rover had already confirmed that it found strong evidence that, yes, ancient Mars may have been able to support life.
By examining the grounds of Gale Crater, where it landed, the rover discovered that Mars was a lot warmer and wetter in the past. Curiosity even found evidence of a rushing river and life-supporting chemicals! And all of this was before the rover reached its intended location to research.
Curiosity’s work is especially fascinating because it represents the epitome of technology, exemplifying our uniquely human ability to create tools to reach heights that our humanness would otherwise have limited. As Jim Green, director of NASA’s Planetary Science Division, commented, Curiosity now begins “a new chapter from an already outstanding introduction to the world”, and we can’t wait to read this new chapter.
Click the picture above to read more about the Curiosity rover at NASA.gov.
Submitted by Aram H., Discoverer
Edited by Peggy K. and Yi Z.