Science News Update: May 2nd

Science News for the Science Classroom

herbivore ancestors Earliest Ancestor of Land Herbivores Discovered

Eocasea martini never ate plants. At only 20 centimeters long, the 300-million year old synapsid- an ancient ancestor to today’s mammals- was entirely carnivorous, feeding on other early land mammals much like every other animal at the time. What makes the otherwise unassuming fossil of Eocasea martini unique is that it is believed that Eocasea martini the one of the earliest known examples of a land herbivore.

Interestingly enough, not all herbivores descend from Eocasea martini. The scientists who discovered Eocasea’s fossil also found that herbivores evolved separately five different times- and twice in reptiles. Therefore, rather than being the ancestor to all herbivore species, Eocasea martini served as a kind of gateway for later herbivore evolution.



harvestmen eyesEyes in ancient “Spiders”

Harvestmen, known also as “Grandaddy Longlegs” in America and the United Kingdom, are a kind of arachnid that remarkably resembles spiders but in fact is more closely related to the scorpions. In addition to having a single fused body rather than two separate body and head segments, Harvestmen have only a single set of median eyes, whereas spiders possess both median and lateral eyes, although this wasn’t always the case.

Because arachnid bodies fossilize poorly, the fossil record of species like spiders and harvestmen is scarce, and their evolution cast in shadow. However, when scientists recently analyzed the fossilized body of a 305 million year old harvestman known as Hastocularis argus, they found that harvestmen once possessed both lateral and median eyes- much like spiders today.

With so little known about the evolution of arachnids, even a finding as seemingly small as this helps shed light on the fossil record, and opens new doors towards further discoveries of ancient spiders, harvestmen, and scorpions.

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sperm receptorThe Receptors Responsible for Life

While it has been known for nearly 50 years that only one sperm can fertilize a given egg, the actual way the sperm recognizes the egg has long been a mystery. Recently, scientists have discovered the two proteins responsible for the attraction of the sperm to the egg- nicknamed “Juno” and “Izumo”, found on the egg and sperm cells, respectively.

When these two proteins were turned off in mice, infertility occurred as the male sperm cell was unable to find the female egg cell. Furthermore, scientists found that when a sperm cell connects to an egg, the “Juno” protein disappears- preventing other sperm from finding the egg.

Today, 20% of infertile women are infertile without a cause. Scientist believe that this discovery could help improve fertility in these women by turning on the potentially dysfunctional Juno protein in their egg cells.

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specialized shark jawsShark Jaws

Sharks are often thought to be a kind of living fossil, species that have evolved little from their primitive origins. Sharks are often taught in textbooks and in classrooms to have remained virtually unchanged since their beginnings over 300 million years ago- an idea long supported by the fossil record, as cartilaginous fish like sharks often fossilize flat, given scientists little opportunity to examine 3D structures such a jaws.

A recently studied 3 dimensional fossil of a an ancient kind of shark Ozarcus mapesae, which lived 305 million years ago, may be the exception to this rule. By not fossilizing flat, scientists were able to compare Ozarcus’ jaw structure to modern sharks. In doing so, they found that Ozarcus’ jaw more resembled that of ancient bony fish to modern sharks- defying the notion that sharks are a primitive, slowly evolving species. In fact, in some ways they may be more advanced and specialized than later vertebrates.



Our latest video explains how three-parent in vitro fertilization may be used to prevent some forms of mitochondrial diseases. Watch for an article next week that helps explain this process in more detail.



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