Background: Dinosaurs didn't totally disappear from earth. They live on today as birds. The reptiles you see today are a relatively separate line of evolution. We can group all birds and reptiles into a monophyletic group (thus birds really are reptiles), and the birds would be today's remnant of dinosaurs.
But birds have beaks. That means that some developmental pathways changed that used to be used for teeth development. To test this idea, scientists inhibited certain pathways thought to be responsible for this transition to beakiness, and the result was a chicken with teeth. The ancestral dinosaur phenotype has been restored.
So this is a fascinating result speaking to the mechanisms behind major evolutionary transitions.
Important note: Picture shown in article heading below is an artistic representation. The birds were never hatched out in this study.
Here is the primary source:
"A molecular mechanism for the origin of a key evolutionary innovation, the bird beak and palate, revealed by an integrative approach to major transitions in vertebrate history"
by Bhullar et al.
Evolution (2015), online first
The avian beak is a key evolutionary innovation whose flexibility has permitted birds to diversify into a range of disparate ecological niches. We approached the problem of the mechanism behind this innovation using an approach bridging paleontology, comparative anatomy, and experimental developmental biology. First we used fossil and extant data to show the beak is distinctive in consisting of fused premaxillae that are geometrically distinct from those of ancestral archosaurs. To elucidate underlying developmental mechanisms, we examined candidate gene expression domains in the embryonic face: the earlier frontonasal ectodermal zone (FEZ) and the later midfacial Wnt-responsive region, in birds and several reptiles. This permitted the identification of an autapomorphic median gene expression region in Aves. In order to test the mechanism, we used inhibitors of both pathways to replicate in chicken the ancestral amniote expression. Altering the FEZ altered later Wnt responsiveness to the ancestral pattern. Skeletal phenotypes from both types of experiments had premaxillae that clustered geometrically with ancestral fossil forms instead of beaked birds. The palatal region was also altered to a more ancestral phenotype. This is consistent with the fossil record and with the tight functional association of avian premaxillae and palate in forming a kinetic beak.
[ #evolution #science #biology #paleontology #dinosaurs #development #evodevo #devoevo #nature #research #news #birds #chicken #teeth #beak #developmentalbiology #evolutionarybiology ]
Skógafoss (pronounced [ˈskou.aˌfɔs]) is a waterfall situated on the Skógá River in the south of Iceland at the cliffs of the former coastline. After the coastline had receded seaward (it is now at a distance of about 5 kilometres (3.1 miles) from Skógar), the former sea cliffs remained, parallel to the coast over hundreds of kilometres, creating together with some mountains a clear border between the coastal lowlands and the Highlands of Iceland.
The Skógafoss is one of the biggest waterfalls in the country with a width of 25 metres (82 feet) and a drop of 60 m (200 ft). Due to the amount of spray the waterfall consistently produces, a single or double rainbow is normally visible on sunny days. According to legend, the first Viking settler in the area, Þrasi Þórólfsson, buried a treasure in a cave behind the waterfall. The legend continues that locals found the chest years later, but were only able to grasp the ring on the side of the chest before it disappeared again. The ring was allegedly given to the local church. The old church door ring is now in a museum, though whether it gives any credence to the folklore is debatable.
At the eastern side of the waterfall, a hiking and trekking trail leads up to the pass Fimmvörðuháls between the glaciers Eyjafjallajökull and Mýrdalsjökull. It goes down to Þórsmörk on the other side and continues as the famous Laugavegur to Landmannalaugar.
There are seven species of #seaturtles,they are the Leatherback Sea Turtle, Green Sea Turtle,Loggerhead Sea Turtle,Kemp's Ridley Sea Turtle ,Hawksbill Sea Turtle,Flatback Sea Turtle and Olive Ridley Sea Turtle .
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#waterfalls #waterfallphotography #brazil #unesco #iguassu #enjoyyourtime
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