Don Davis/NASA

Scientists from 12 nations contend that an asteroid was responsible for the mass extinction that killed 50 to 70 percent of all species on Earth. They claim that geological evidence links the asteroid impact in Chicxulub, Mexico, to the timing of the Cretaceous-Paleogene (K-Pg) extinction. These findings contradict alternate explanations for the mass extinction, such as the volcanic and dual-impact theories.

The asteroid collided with the Earth more than 65 million years ago and its impact led to the extinction of terrestrial and flying dinosaurs, large marine reptiles and various plant species. This event paved the way for mammals to become Earth's dominant species. One of the major pieces of evidence supporting the asteroid theory was the discovery of high levels of iridium in earth samples from the time of the extinction. Iridium is found in high concentrations in asteroids and comets. Another piece of information that linked the mass extinction to the asteroid impact was the presence of shocked minerals in geological records. Shocked minerals are found at nuclear explosion and meteorite impact sites.

Learn more about this discovery:

• Revisiting Chicxulub National Science Foundation

Reconstruction of the fossilized nest. Sculpture by Tyler Keillor and original photography by Ximena Erickson; image modified by Bonnie Miljour

Researchers from the Geological Survey of India have discovered fossil evidence that suggests that some snakes ate baby dinosaurs. The primitive snake known as Sanajeh indicus was about 11.5 feet long. Its fossilized skeletal remains were found inside the nest of a titanosaur. The snake was coiled around a crushed egg and near the remains of a titanosaur hatchling. Titanosaurs were plant-eating sauropods with long necks that grew to an enormous size very quickly.

The researchers believe that these dinosaur hatchlings were easy prey for Sanajeh indicus. Due to the shape of its jaw, this snake was unable to consume titanosaur eggs. It waited until the hatchlings emerged from their eggs before it devoured them. Although originally discovered in 1987, it wasn't until years later that the fossilized nest was recognized to include the remains of the snake. Paleontologist Jeff Wilson states, "Burial (of the nest) was rapid and deep. Probably a pulse of slushy sand and mud released during a storm caught them in the act." The discovery of the fossilized nest gives us a glimpse of a moment in time during the Cretaceous period.

Learn more about this discovery:

• Fossil Snake from India Fed on Hatchling Dinosaurs Science Daily

Image: Suat Eman FreeDigitalPhotos.net

The integumentary system consists of the largest organ in the body, the skin. This extraordinary organ system protects the internal structures of the body from damage, prevents dehydration, stores fat and produces vitamins and hormones. It also helps to maintain homeostasis within the body by assisting in the regulation of body temperature and water balance.

The integumentary system is the body's first line of defense against bacteria, viruses and other microbes. It also helps to provide protection from harmful ultraviolet radiation. The skin is a sensory organ in that it has receptors for detecting heat and cold, touch, pressure and pain. Components of the skin include hair, nails, sweat glands, oil glands, blood vessels, lymph vessels, nerves and muscles.

To learn more about human anatomy and organ systems of the body, see:

• Digestive System
  
• Circulatory System
  
• Nervous System
  
• Organ Systems Quiz

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Carbon monoxide (CO) is a colorless, odorless, tasteless and toxic gas produced as a by-product of combustion. Any fuel burning appliance, vehicle, tool or other device has the potential to produce dangerous levels of carbon monoxide gas. Examples of carbon monoxide producing devices commonly in use around the home include fuel fired furnaces, gas stoves and dryers, lawnmowers and automobiles.

Carbon monoxide is so dangerous because it inhibits the blood's ability to carry oxygen to body tissues including vital organs such as the heart and brain. When CO is inhaled, it combines with the oxygen carrying hemoglobin of the blood to form carboxyhemoglobin (COHb). Once combined with the hemoglobin, that hemoglobin is no longer available for transporting oxygen. Symptoms from carboxyhemoglobin build up can range from a mild headache to unconsciousness and death.