23 July 2016
The animal for the month on the calendar will feature this week as this is the last full week of July. That dinosaur happens to be one of the largest on the calendar as well and it is also one of the dinosaurs that we have focused on multiple times here. There is almost never enough in one week, so discussing one animal three times is not actually a problem as it allows us to felve even deeper into the knowledge about this specific dinosaur. The dinosaur astronaut of the week is a whale of a dinosaur: Apatosaurus ajax.
22 July 2016
21 July 2016
Protoavis has never fully ascended to the popularity of an animal that was whole or to the kind of animal that Protoavis really had the potential to be. Lacking the solid evidence that proves that the fossil is or is not a chimeric group of fossils, we can never be entirely sure of the nature of Protoavis. If it is a very early bird it pushes back the origin of birds into another age (the Triassic) and makes birds even more ancient than previously thought. If it is a theropod, but not a bird, then Protoavis is a bipedal dinosaur well on its way to the building blocks of bird origins despite not being a bird. The alternative, that it is a group of fossils, makes the remaining material of little use and uninformative. Whatever one decides, there is a lot of literature that needs to be examined in order to make an informed decision.
20 July 2016
There are many assertions made from as many angles about the remains of Protoavis from the fossil's head to its toes and tail. Starting at the skull, it is described as complete by Chatterjee, though the known fossil is recognized to be missing much of the rostral aspect forward of the temporal region. Additionally, Chatterjee made many observations of the quadrate and its mobility. Subsequent observations and descriptions by Paul, Chatterjee, Ostrom, and others have not validated the shape, articulation, or mobility of the quadrate within the specimens of Protoavis that have been described. The braincase is similarly marred by disagreement. Disagreements are made with the cervical vertebrae and some of the other post-cranial elements, but none as much as the quill knobs that Chatterjee mentions on the broken ulna of the type specimen. The inclusion of these supposed quill knobs caused an inference of feathering and that is why current illustrations depict Protoavis as being a small feathered dinosaur. Many subsequent descriptions of the same anatomy have concluded that the material, because it is fragmentary, cannot be confidently described as possessing quill knobs and flight feathers. Whether this is truly the case or not we may not know for a very long time, if ever, but the image of a feathered Protoavis is normal whereas a non-feathered Protoavis is not common and may not even exist.
19 July 2016
The original description of Protoavis is not online. There are mentions of Protoavis in many different places including a short review of bird evolution by Luis Chiappe. This review mentions the first 85 million years of bird evolution; we know that there is far more to the bird evolution story than just 85 million years. The bird is also mentioned many times in Sankar Chatterjee's The Rise of Birds. Chatterjee mentions Protoavis multiple times, probably because he did the original description. However, he does mention it in relative situations and for good reason. Appropriate mention of your own described taxon is tasteful and worth appreciating.
18 July 2016
17 July 2016
Despite the contentious nature of the Protoavis fossil there are multiple websites dedicated to presenting facts about this odd fossil. Most of the sites directly address the controversy. Dinosaur Facts is one such site that addresses the controversy and offers an opinion. That site is more direct in its opinion than About, which mentions that there is controversy but does not take a side or voice a strong opinion either way. There are also sites that barely mention or may entirely ignore the controversial fossil material like Dinosaur Jungle. If the controversy itself is high on your list of interests, EvoWiki has a page dedicated to just the evidence from both sides of the argument.