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Archaeopteryx Fossil


The Archaeopteryx was an ancestor of the Albatross, and indeed, of all living birds today. It had lived from between 150 - 145 million years ago, during the late Jurassic period. It was one of the earliest animals in recorded history to have some sort of feathers, and one of the first animals with the ability to glide and fly for short distances. However, it still has characteristics that resemble more like small dinosaurs than modern birds. From the Archaeopteryx, Birds diversified and evolved into everything from the Little Penguin to the Kea , the Procellariformes order, containing the Wandering Albatross, is speculated to have branched out from between 30 - 35 million years ago, with the lineage that would contain the modern day Albatrosses separating from the lineages that would evolve into the modern-day diving-petrels and storm-petrels.


Scientific Classification Table


Kingdom
Animalia
Phylum
Chordata
Class
Aves
Order
Archaeopterygiformes
Family
Archaeopterygidae


Species
Archaeopteryx


Habitat

The only Archaeopteryx specimens have been found in Bavaria, Southern Germany (see Fig.2), and was dated to be from about 150 - 140 million years ago, in the late Jurassic era. The climate back then was much more warm than in the present day, tropical and sub-tropical conditions extended more northwards than today, while there is evidence for temperate conditions occurring in the polar regions of today. There has been no evidence of polar ice caps, which meant that ocean levels were much higher than they are today. The habitat that Archaeopteryx had lived in ancient times was found to have a similar latitude to Florida, besides Archaeopteryx, there were also many other types of flora and fauna found in the Fossil Records where Archaeopteryx was found. There were types of conifers and cycads in the area, while there were also insects, small lizard and primitive mammals, similar in size to modern Rats, in the area.

The islands that surround where Archaeopteryx is speculated to have lived were low-lying, semi-arid, in a sub-tropical climate with a long dry season, that normally experiences very little rain. The plants of the island were well adapted to the dry conditions on the island and consisted of low, dry shrubs, with very little trees in between. The Albatross is similar in size to the European Magpie, it could grow up to approximately 0.5 metres (1.6 ft) and weigh about 5 pounds, however, structurally, the Archaeopteryx is more similar to small theropod dinosaurs, like the Deinoschyus, than the modern birds. The long legs and the toothed beak mean that the Archaeopteryx will have very little problems with walking on land , using the wings by climbing to the tops of trees and gliding down as a long-distance alternative, as the fossils of the Archaeopteryx point to it having chest and shoulder muscles that are too weak for full-fledged flying.

The Archaeopteryx, living in the diverse habitat, probably had great varieties of prey to choose from, there would have likely been many insects that are hidden underground or in the shrubs, while there may be primitive mammals that may also be hiding in bushes or in the trees, small lizards, similar to the gecko may be found in the trees, while in the lagoon, primitive fish may be able to be found. However, with the large number of possible prey, there may be a large number of potential predators for the Archaeopteryx as well, as its size does not point to it being the apex predator of its food chain. Large carnivorous dinosaurs had been known to exist in the period when Archaeopteryx existed, and an Archaeopteryx may be prey to small raptors on land.

The lifestyle of Archaeopteryx is a topic that divides many experts. Some researchers suggest it primarily lived its life on the ground, while others suggested it flew frequently in the air. The characteristics of the Archaeopteryx partially support both of these claims, this suggests that Archaeopteryx was more of a generalist, capable of feeding in many varied environments such as in shrubs, open areas and along the shores of the lagoon. Archaeopteryx, like its modern descendent, was carnivorous, it probably hunted small prey that is hiding in the shrubs and in the water, taking with its jaws or by holding prey with its claws.

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Figure 2: The world 150 million years ago


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The environment that Archaeopteryx lived in


Adaptations

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Figure 1: Physical features of the Archaeopteryx

Physical Adaptation 1:

One of the most notable (at the time) physical adaptations of the Archaeopteryx was that it was the first animal to have well developed feathers designed for flight in the wings. These feathers share similarity with the structure of flight feathers in modern birds, In addition to this, there were also feathers found on the tail and the neck of the animal. This a great departure from the dinosaurs that the Archaeopteryx evolved from, as they primarily used keratin, in the form of scales for their outer layer and protection. The change from scales to feathers for the outer layer of the animal had probably arisen due to a need to lighten the animal, in order for it to gain the essential component of flight. One environmental pressure for the animal to gain flight may have been to escape from the predators on the ground, the animal would have to develop a means of escape, and flying was the solution.

Physical Adaptation 2:

Another notable physical adaptation that the Archaeopteryx possesses is that it has a relatively large forelimb for the time, the proportion of the forelimb to the body was noticeably larger than most dinosaurs in that period of time. The bones in the forelimbs were also relatively hollow, bearing similarity to modern birds, and different from the bones of reptiles at the time, which were solid. The light and long forelimb provided space for large muscles to attach to the bones, providing the necessary strength needed in order for Archaeopteryx to fly, the long forelimb also meant the wings that Archaeopteryx has are longer and wider, increasing their surface area, which would allow for better maneuverability in the air. The environmental pressure for this may be that Archaeopteryx was gliding from tree to tree, the longer forelimbs allow for more surface area in the wings, which allowed further gliding distances, over time, this may have developed into full-fledged flight.

Behavior Adaptation 1:
A notable behavior adaptation that Archaeopteryx possessed was that it is a generalist feeder, it is capable of feeding in shrubs, open ground, and in the coastlines of its habitat, running down small lizards and animals in open ground and near the coastline, picking insects off trees and shrubs, and occasionally robbing bests of small dinosaurs in the bushes. The body of Archaeopteryx supports this claim, as it doesn't seem to be specialised in any form, with long legs for running on the ground, wing claws for holding prey, and claws on the legs for gripping on trees, it is clearly adapted to life on the ground as well as in the air, this may have happened in order for Archaeopteryx to have a greater chance of survival in varied environments. An environmental pressure that may have gave rise to this was the varied environment of Archaeopteryx's habitat, it would be preferable for the animal to be more general and versatile rather than become specialized in a certain habitat, because if that specific habitat becomes nonexistant, the generalist will still have other habitats to live in.

Behavior Adaptation 2:
Another behavior adaptation that Archaeopteryx had was that it was primarily a carnivorous creature, which was shown clearly by the toothed beak that it possessed, which contained teeth that were used for slicing, essential for carnivorous creatures to have. This is inherited from the Archaeopteryx's ancestor, the Deinochyus, which was a carnivorous animal and hunted small animals. The environment of that time may also have favored large carnivorous animals over herbivorous animals of the same size, because meat is much more energy dense than plants, an animal would need to consume a lot less meat in order to match the energy in plants, this has the potential to free up Archaeopteryx from using time to eat to focus on other things. The environmental pressure for being a carnivore could be that the plants in the habitat of Archaeopteryx were hard to digest for the animal, and the amount of effort that it took to catch the animals was comparatively less than the amount of time it took for the animal to feed itself on plants.

Physiological Adaptation

A Physiological Adaptation that Archaeopteryx developed in order to pursue its need to fly is its enlarged brain. Its brain was much larger than contemporary dinosaurs of the time, enough for it to possess the necessary brain size for flight. The visionary region of Archaeopteryx's brain took up nearly a third of the brain, with a large proportion of the brain that is dedicated to hearing and muscle co-ordination as well. The Inner Ear structure of Archaeopteryx was also more in resemblance of modern birds than reptiles. They have evolved in order to give Archaeopteryx the necessary spatial perception and co-ordination for flying. The environmental pressure that may have given rise to this was the fact that in flight, the Archaeopteryx will have to maneuverer in 3 dimensions, an extra dimension compared to when only walking, so the brain will have to process more things.

Extinction Pressure
There is no clear and definite reason why Archeopteryx had eventually became extinct, the fossils that hold Archaeopteryx fossil remains are old, and there is no solid evidence that can be deduced to point the reason for its extinction to one way or another. It probably didn't go extinct in the "traditional" sense, where all members of the species died out. As the species of Archaeopteryx evolves and diversifies into many different species of birds, the original form of Archaeopteryx no longer exists, so it can be seen as being extinct. Another theory for the extinction of the Archaeopteryx is that as the geological period gradually shifted from the Jurassic period to the Cretaceous period, the climate had encountered a significant change, the weather had become colder, with ice in the earths poles and the tropics have gotten much wetter, this would encourage plant life, and consequently, animals would grow larger in response to the increasing food supply, combine that with a possible land bridge due to falling sea levels and there may have been a large influx of larger dinosaurs that out-competed Archaeopteryx in its role.

Links
Wandering Albatross
References
Chiappe, Luis M. (2007). Glorified Dinosaurs. Sydney: UNSW Press. pp. 118–146. ISBN 0-471-24723-5.
Longrich N. (2006): Structure and function of hindlimb feathers in Archaeopteryx lithographica. Paleobiology. 32(3): 417–431. doi:10.1666/04014.1(HTML abstract)
Witmer, L. M. (2004). Palaeontology: Inside the oldest bird brain. Nature. 430(7000): 619–620. PMID 15295579 doi:10.1038/430619a
Alonso, P. D., Milner, A. C., Ketcham, R. A., Cookson, M. J. & Rowe, T. B. (2004). //The avian nature of the brain and inner ear of Archaeopteryx//. Nature.430(7000): 666–669. PMID 15295597. doi:10.1038/nature02706. PDF fulltext Supplementary info

http://www.dinosauria.com/jdp/archie/wings.htmNedin, C. (1999, January 15). All about Archaeopteryx. Retrieved from http://www.talkorigins.org/faqs/archaeopteryx/info.html