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A structure that is not harmful will take longer to be 'phased out' than one that is. However, some vestigial structures may persist due to limitations in development, such that complete loss of the structure could not occur without major alterations of the organism's developmental pattern, and such alterations would likely produce numerous ...
Flowering plants (Delphinium, Aerangis, Tropaeolum and others) from different regions form tube-like spurs that contain nectar. This is why insects from one place sometimes can feed on plants from another place that have a structure like the flower, which is the traditional source of food for the animal. [218]
Remnant eyes (and eye structures) in animals that have lost sight such as blind cavefish (e.g. Astyanax mexicanus), [88] mole rats, snakes, spiders, salamanders, shrimp, crayfish, and beetles. [89] [90] Vestigial eye in the extant Rhineura floridana and remnant jugal in the extinct Rhineura hatchery (reclassified as Protorhineura hatcherii ...
Large, well-developed limbs increase drag on swimming animals, so the limbs of Eupodophis and other early snakes may have become vestigial to save energy and make movement more efficient. No vestigial limbs whatsoever are present in the modern species, which lack transitional species remnants. What few species have them protrude as tiny spurs.
X-ray showing the skeleton of Typhlonectes (Typhlonectidae). Caecilians' anatomy is highly adapted for a burrowing lifestyle. In a couple of species belonging to the primitive genus Ichthyophis vestigial traces of limbs have been found, and in Typhlonectes compressicauda the presence of limb buds has been observed during embryonic development, remnants in an otherwise completely limbless body. [7]
Pelvic spurs (also known as vestigial legs) are external protrusions found around the cloaca in certain superfamilies of snakes belonging to the greater infraorder Alethinophidia. [1] These spurs are made up of the remnants of the femur bone, which is then covered by a corneal spur, or claw-like structure. [ 1 ]
Tetrapod footprints found in Poland and reported in Nature in January 2010 were "securely dated" at 10 million years older than the oldest known elpistostegids [33] (of which Tiktaalik is an example), implying that animals like Tiktaalik, possessing features that evolved around 400 million years ago, were "late-surviving relics rather than ...
One fundamental subgroup of amniotes, the sauropsids, diverged into the reptiles: lepidosaurs (lizards, snakes, and the tuatara), archosaurs (crocodilians and dinosaurs, of which birds are a subset), turtles, and various other extinct forms. The remaining group of amniotes, the synapsids, include mammals and their extinct