I'm just a Paleobiology major trying to share the beauty of the past, praise silt, and all of its wonders yet to be uncovered.

 

Herrerasaurus

Herrerasaurus (Herrera’s Lizard after the rancher who discovered it) was an early theropod dinosaur that lived in the middle Triassic. For a long time it was unclear what the classification of Herrerasaurus was, as the remains found were very incomplete. It was hypothesized to be a basal Theropod, a basal Sauropodomorph, a basal Saurischian, and even not a dinosaur at all, however, with the discovery of a nigh complete specimen in 1988, it has been decided to either be an early Theropod or early Saurischian, with most researches treating it as the former. 

Herrerasaurus was carnivorous and grew to be approximately 1 meter tall, at the hip, and to a length of 3 to 6 meters. It had a long, narrow skull, lacking nearly all specializations and characteristics of later dinosaurs, and more closely resembled an early Archosaur skull. It had a flexible lower jaw that allowed it to slide back and forth to deliver a grasping bite. It also had a long slender neck, and large serrated teeth, for biting and eating flesh. It’s arms were short, being less than half the length of leg. The upper and forearms were short, however, it had elongated hands, with the first two fingers and thumb curving inwards, and the last two being claw-less stubs. It was full bipedal, unlike most reptiles of the time, it had strong hind limbs with short thighs and long feet, indicating that it was likely a swift runner. Its foot had five toes, the first and fifth toes being stubs, and second through third toes being the only ones that actually bore weight. The tail, stiffened by overlapping vertebrae, acted as a balancing mechanism and was also an adaptation that helped increase the beast’s speed.

Fossil:

By Eva K. (Eva K.) [GFDL 1.2 (www.gnu.org/licenses/old-licenses/fdl-1.2.html) or FAL], via Wikimedia Commons

Model:

By Eva K. (Eva K.) [GFDL 1.2 (www.gnu.org/licenses/old-licenses/fdl-1.2.html) or FAL], via Wikimedia Commons

Living Fossils - Liphistiidae

Liphistiidae is a family of spiders that contains 5 genera and 85 species, now you might be thinking that that isn’t very meaningful taxonomically, but this family of spiders is extremely basal, which if you’ll remember, is the main factor which classifies an organism as a living fossil.

These spiders are non-venomous and live in tubes, and should not be confused with Trapdoor spiders, or other spider families that also live in burrows, tubes, or crevices. These spiders are characterized by their downward pointed chelicerae (mouth parts,) and segmented series of plates on their abdomens. They are nocturnal, and the males wander searching for females, who generally stay in their burrows, waiting for prey. They have low activity, which may be because they have book lungs. They may also be found in caves where they live in natural retreats, which are still sealed off with a rudimentary silken door. Pictured above is the well known Kimura-gumo (Heptathela kimurai,) of Japan, and I believe both are female.

In burrow:

By Akio Tanikawa (http://spider.fun.cx/okinawa/yanbarukimuragumo.htm) [CC-BY-SA-2.5 (www.creativecommons.org/licenses/by-sa/2.5)], via Wikimedia Commons

Spider:

By Akio Tanikawa (http://spider.fun.cx/okinawa/yanbarukimuragumo.htm) [CC-BY-SA-2.5 (www.creativecommons.org/licenses/by-sa/2.5)], via Wikimedia Commons