maniraptorans

Nipponoolithus

Nipponoolithus is a fossil egg known from Japan, specifically the Sasayama group in Kimitaki, Tamba, Hyogo, Japan. It comes from the Albian age of the Early Cretaceous. It is a very small egg, known from only a handful of fragments from between. 36 to .53 mm thick. It probably would have weighed about 100 grams, making it one of the smallest fossil dinosaur eggs ever known. It was probably laid by a Maniraptoran of some sort based on its structure and ornamentation. 

Source:

https://en.wikipedia.org/wiki/Nipponoolithus

Shout out goes to @we-cracked-the-sky!

twerkyvulture  asked:

Have you talked about Alvarezsaurus and it's cute lil tip tappy lil claws yet

The alvarezsaurs are a fairly recently known group of dinosaurs; the first alvarezsaur fossil was discovered in 1975, and the family Alvarezsauridae was first named in 2010.  As a result, they are still somewhat obscure - due in part to their strange anatomies.

Alvarezsaurs - like Shuvuuia, pictured above by FunkMonk - are known for their one-fingered hands.  Among alvarezsaurs, the second digit of the hand had grown to massive proportions, while the other fingers dwindled away.  The single giant finger was not vestigial, like the digit bones in the wing of a bird; it was a perfectly usable digit, tipped with a large and powerful claw.  Therefore, the single finger had to have some use; the question is, what?

The shortness of the arm precluded the claw from being used as a digging tool, so alvarezsaurs likely did not burrow or break open termite nests.  However, their elongated, tubular skulls and numerous tiny teeth have been interpreted as adaptations for insectivory.  They may have used their claws to strip bark from trees, searching for wood-boring insects.

The image below depicts Haplocheirus, the oldest known relative of the alvarezsaurs, doing just that.  Technically an alvarezsauroid (not a true alvarezsaur), Haplocheirus had three well-developed fingers, but its anatomy was otherwise quite similar to that of its descendants.  It’s speculated that Haplocheirus was a generalist animal, and that its descendants became more and more specialized for insect-eating over time.

(Image by Nathan Rogers.)

The alvarezsaurs were initially considered to be avians, due to numerous bird-like skeletal features, including their keel-like sternums and fused hand and wrist bones.  However, the discovery of more primitive alvarezsaurs and alvarezsauroids proved this to be incorrect.  The alvarezsaurs are now considered to be the most basal maniraptorans, related to therizinosaurs and pennaraptorans.  The presence of birdlike features in such a primitive group of maniraptorans shows that such traits evolved multiple times within the group.

Another birdlike trait of the alvarezsaurs is the presence of feathers.  Chemical analysis of fossilized alvarezsaur feathers revealed for the first time that dinosaur feathers and bird feathers were composed of the same types of keratin proteins.

Dispersituberoolithus

Dispersituberoolithus is a fossil egg genus known from the Campanian age of the Late Cretaceous. It was found in the Oldman Formation in Alberta, Canada, and was probably laid by some sort of Maniraptoran theropod, potentially an Avialan. It is known from sheveral eggshell fragments and they had randomly distributed nodes on the eggshell. It had an eggshell thickness of about .26 to .28 mm, and the shell itself had three layers. 

Source:

https://en.wikipedia.org/wiki/Dispersituberoolithus

Shout out goes to @kandiviper!

2

The Red rail (Aphanapteryx bonasia) was the largest of Mauritius’ rails and certainly the strangest in appearance. Similarly to the dodo and many other birds native to the Mascarene islands, it was completely flightless, and its small wings would have been concealed in life beneath its shaggy, reddish-brown plumage. The only physical remains known from this species are its pelvis and leg bones, which makes it difficult to gauge its full size in life, but contemporary accounts compare it in size to a large hen. Within the rail family, its closest relative seems to be the Rodrigues rail (Erythromachus leguati), also extinct. More distantly, it is allied with the White-throated rail (Dryolimnas cuvieri) of Madagascar, the Seychelles, and Comoros, which today appears to be the only endemic flightless bird remaining on the Indian Ocean’s islands.

Its slender, vaguely ibis-like bill suggests a cursorial foraging lifestyle, preying on small invertebrates. The now-extinct land snail Tropidophora carinata, also endemic to Mauritius, appears to have been one such prey item, as some subfossilized shells belonging to this species carry blunt damage marks consistent with this bird’s beak.

Sadly, very little is known for sure about the Red rail, since like many other flightless birds of the world’s oceanic islands, it became extinct a short time after humans colonized its home. The tropical forests of Mauritius began to shrink after the island was claimed by the Dutch East India Company in the 17th Century, spelling doom for this rail, the dodo, and many others, as overhunting and deforestation disrupted their habitat. By 1700, the Red rail had disappeared forever.

Puzzling over this flightless rail and the dodo, centuries before Darwin’s On the Origin of Species, English adventurer Peter Mundy observed:

“Of these 2 sorts off fowl afforementionede, For oughtt wee yett know, Not any to bee Found out of this Iland, which lyeth aboutt 100 leagues From St. Lawrence. A question may bee demaunded how they should bee here and Not elcewhere, beeing soe Farer From other land and can Neither fly or swymme; whither by Mixture off kindes producing straunge and Monstrous formes, or the Nature of the Climate, ayer and earth in alltring the First shapes in long tyme, or how.”

Sources: [x]  [x]

Images: Above: a plate by Frederick William Frohawk (1861 - 1946), wildlife artist; via Wikimedia Commons. Below: sketch of a hunted specimen ca. 1601, attributed to one Joris Joostensz Laerle; via Wikimedia Commons.

Oblongoolithus

Oblongoolithus is a theropod dinosaur egg genus known from the Barun Goyot Formation in southern Mongolia. They are similar to elongate eggs with long, ovular eggs, but they have smooth shells unlike elongate eggs. The eggs come from the late Cretaceous and were probably laid by some sort of Maniraptoran. 

Source:

Carpenter, K. 1999. Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past). Indiana University Press, Bloomington, Indiana.

Shout out goes to @kupkeiksitomjo!