Study of Fossil: Archaeopteryx
Archaeopteryx lithographica fossil, found in the Jurassic Solnhofen Limestone of southern Germany
Systematic Position: (J.Z.Young,1981)
Kingdom: Animalia
Phylum: Chordata
Sub Phylum: Vertebrata
Super Class: Gnathostomata
Class:Reptilia
Sub Class: Archosauria-Archaeornithes
Order: Archaeopterygiformes
Genus: Archaeopteryx
Origin:
Late Jurassic period abour 140 Million years ago.
Archaeopteryx lithographica
Ancient wing
Discovered near Bavaria,Germany.
Characters:
Reptilian characters:
Non pneumatic bones.
Strong jaws are provided with homodont peg like teeth lodged in sockets.
One long, tapering, lizard like tail composed of about 20 free caudal vertebrae. No pygostyle.
Presence of Amphicoelous vertebrae as in Sphenodon.
Each forelimb bears 3 free clawed fingers having typical reptilian number of phalanges.i.e.2,3& 4 in the first, second and third fingers respectively.
Sternum poorly developed, without keel.
Body covered with well developed contour and flight feathers.
Forelimbs modified as wings for flight, bearing remiges and 3 digits each.
Tail bears elongated rectrices, arranged in two lateral rows.
Presence of monocondylic skull with large round brain case
Tibia and fibula are found separate.
Bones of girdles and limbs are bird like with elongated curved Scapulae and V-shaped furcula.
Evolutionary Significance:
It exhibit both reptilian and avian characters and maintain a connecting link between both.
It had a general resemblance with Archosaurian reptile but not true reptile as well.
Its reptilian features are the presence of teeth in jaws, a long tail with free caudal vertebrae, and a weak and keel-less sternum.
Its avian characters include the presence of feathers on the body, forelimbs modified into wings and four foes in foot adapted for perching. This suggested that birds have evolved from reptilian ancestors.
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