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Your Inner Fish

Submitted by crmckenzie on Fri, 02/09/2018 - 19:17

"Your Inner Fish" is the first episode of a documentary series about a vertebrae paleontologist named Neil Shubin. The focus of this episode is to discuss how humans evolved from fish. It considers Darwin's common ancestor theory and talks about how the same basic structure of forelimbs exists in both mammals and their fish-like ancestor. Birds and reptiles also share this common ancestor. There are significant similarities between the human embryo and the fish embryo. The portion of the human embryo that corresponds to gills in the fish embryo forms the lower jaw, middle ear, and voice box in humans. This correspondance represents the developments of evolution. A gene called hedgehog tells cells how to carry out events in a specific order during development. When this gene is overexpressed, it can result in extra fingers. When underexpressed, it can result in less than five fingers. The episode ends on the Tiktaalik, the missing link in the line of evolution between fish and humans. This is the creature that paleontologists have been searching for as it has the same forelimb pattern as humans.

 

Increased Fire Risk in Southwestern USA

Submitted by mduque on Fri, 02/09/2018 - 14:49

Because tree growth rings vary in width with annual precipitation, scientists have used tree rings to reconstruct the fire history of an area for decades. This year, exceptionally dry conditions have been seen in Arizona and rain does not seem to be coming any time soon (which means this area of the country is set up for a dangerously big wildfire in the near future). A wildfire of that magnitude would result with a loss of vegetation that would not only leave the area vulnerable to post-fire flooding that could wipe out roads but could also clog vital water infrastructures that would inevitably lead to the displacement of many people.

Dog Skull

Submitted by cfellrath on Fri, 02/09/2018 - 14:24

Figure 1: C. lupus familiaris skull.

The figure illustrates the structure of common dog’s skull. The skull is two separate parts connected by the mandibular condyle fits into the mandibular fossa. The lateral view of the dog skull shows the different bones that have fused to become whole

 

Dog Skull

Submitted by jngomez on Fri, 02/09/2018 - 14:22

         Medium (640 × 480)        

 

Figure 1. Canis lupus familiaris skull (Dog skull)

Depicted in the image is a labeled skull of a Canis lupus familiaris. It clearly illustrates the carnassial complex. The carnassial complex is a specialized sectorial (cutting) teeth. The upper and lower jaw contain incisors, canine, premolars and molars. In the upper jaw it shows the last upper premolar versus the lower jaw which shows the first lower molar.

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