According to scientist , aves have evolved from: select one:
a. reptiles
b. arthropods
c. mammals
d. amphibians
Answers
Answered by
1
Class- Amphibia
Devonian origin & carboniferous is the age of amphibians
Class amphibia includes amphibious animals which can live on both the places at ease i.e. under water and on the land. No marine.
These are the first chordate animals which come out of water but these are not able to live on land permanently, these depend on water for their reproduction. Their eggs do not have protecting covering to check the evoporation.
Body is divided into head, trunk and tail. Some amphibians lack tail, e.g. frog, toad etc.
Skin is smooth and mostly scale less, but whenever scales are present there are embeded in the skin e.g. Ichthyophis.
Numerous glands are found in skin which help in moistening the skin. So these animals respire through moist skin. Some poisonous glands are also found in the skin of some animals e.g. Bufo.
Pigment cells are also found as chromatophore for colouration. Few amphibians have ability to change colour by expansion and contraction of pigment cells. This phenomenon is known as Metachrosis.
Two pairs limbs help in swimming in water or moving on land. Forelimbs have four fingers and hindlimbs have five fingers.
Their digits do not have nails or claws at all.
Mouth is bigger in size. Upper or both the jaws have alike teeth. These are pleurodont, homodont and polyphyodont. Suspensorium of jaws is autostylic. (Frog - Acrodont)
A well developed and complete alimentary canal along with digestive glands are present in digestive system (Salivary glands are absent in frog).
Alimentary canal, urinary bladder and genital ducts open into cloaca.
Respiration by gills, skin, lungs or buccopharyngeal cavity.
Two nostrils are found, this condition is called dirhynous.
Heart is three chambered. 2 auricles and 1 ventricle (arteriovenous). Sinus venosus and Truncus arteriosus is well developed.
R.B.Cs are biconvex, oval and- nucleated.
In these animals, renal portal system and hepatic portal system are found.
Endoskeleton is made up of bones, but cranium is cartilaginous.
Skull has two occipital condyles, with the help of these two condyles skull is connected by first vertebra of vertebral column i.e, Atlas, this type of skull is called dicondylic skull.
Ribs absent, but may be present in some animals, but ribs are not attached with sternum.
Vertebrae, in these .animals are procoelus type, in which centrum is concave from anterior side and convex from posterior side.
External ear absent, only one ear ossicle columella (stapes) is present in middle ear.
Cranial nerves are 10-pairs.
Lateral line sensory system is necessarily found in any stage of development. In frog it is found only in larval stage.
1 pair of kidneys work as excretory organs. These kidneys are mesonephric' or opisthonephric type. These animals are ureotelic. But tailed animals & larvas are ammoniotelic.
These are cold blooded or poikilothermal animals.
These animals undergo hibernation or aestivation to prevent themselve from extreme cold and heat and to overcome unfavourable conditions.
These are unisexual animals, males have copulatory organs sometimes. These animals return to water from land for their. reproduction.
Fertilization is external and inside the water, but some animals show internal fertilization.
These are oviparous, which lay their eggs in water.
Eggs are mesolecithal. Extra-embryonic membranes are absent, so these are placed under anamniota group.
Cleavage in eggs is holoblastic and unequal.
Development is indirect type i.e. tadpole larva – In Frog: Axolotl larva - In Salamander
This class is divided into three orders:
(A) Gymnophiona or Apoda
(B) Caudata or Urodela
(C) Anura or salientia
(a) Order - Gymnophiona Of' Apoda
Their body is worm like. These are primitive amphibians burrowing in nature.
Their body is limbless.
Skin is soft, and moist, with mucous glands; small scales (cycloid) are found on the skin.
Their eyes are covered by opaque skin. (Blind)
Middle ear and tympanic membrane a
Devonian origin & carboniferous is the age of amphibians
Class amphibia includes amphibious animals which can live on both the places at ease i.e. under water and on the land. No marine.
These are the first chordate animals which come out of water but these are not able to live on land permanently, these depend on water for their reproduction. Their eggs do not have protecting covering to check the evoporation.
Body is divided into head, trunk and tail. Some amphibians lack tail, e.g. frog, toad etc.
Skin is smooth and mostly scale less, but whenever scales are present there are embeded in the skin e.g. Ichthyophis.
Numerous glands are found in skin which help in moistening the skin. So these animals respire through moist skin. Some poisonous glands are also found in the skin of some animals e.g. Bufo.
Pigment cells are also found as chromatophore for colouration. Few amphibians have ability to change colour by expansion and contraction of pigment cells. This phenomenon is known as Metachrosis.
Two pairs limbs help in swimming in water or moving on land. Forelimbs have four fingers and hindlimbs have five fingers.
Their digits do not have nails or claws at all.
Mouth is bigger in size. Upper or both the jaws have alike teeth. These are pleurodont, homodont and polyphyodont. Suspensorium of jaws is autostylic. (Frog - Acrodont)
A well developed and complete alimentary canal along with digestive glands are present in digestive system (Salivary glands are absent in frog).
Alimentary canal, urinary bladder and genital ducts open into cloaca.
Respiration by gills, skin, lungs or buccopharyngeal cavity.
Two nostrils are found, this condition is called dirhynous.
Heart is three chambered. 2 auricles and 1 ventricle (arteriovenous). Sinus venosus and Truncus arteriosus is well developed.
R.B.Cs are biconvex, oval and- nucleated.
In these animals, renal portal system and hepatic portal system are found.
Endoskeleton is made up of bones, but cranium is cartilaginous.
Skull has two occipital condyles, with the help of these two condyles skull is connected by first vertebra of vertebral column i.e, Atlas, this type of skull is called dicondylic skull.
Ribs absent, but may be present in some animals, but ribs are not attached with sternum.
Vertebrae, in these .animals are procoelus type, in which centrum is concave from anterior side and convex from posterior side.
External ear absent, only one ear ossicle columella (stapes) is present in middle ear.
Cranial nerves are 10-pairs.
Lateral line sensory system is necessarily found in any stage of development. In frog it is found only in larval stage.
1 pair of kidneys work as excretory organs. These kidneys are mesonephric' or opisthonephric type. These animals are ureotelic. But tailed animals & larvas are ammoniotelic.
These are cold blooded or poikilothermal animals.
These animals undergo hibernation or aestivation to prevent themselve from extreme cold and heat and to overcome unfavourable conditions.
These are unisexual animals, males have copulatory organs sometimes. These animals return to water from land for their. reproduction.
Fertilization is external and inside the water, but some animals show internal fertilization.
These are oviparous, which lay their eggs in water.
Eggs are mesolecithal. Extra-embryonic membranes are absent, so these are placed under anamniota group.
Cleavage in eggs is holoblastic and unequal.
Development is indirect type i.e. tadpole larva – In Frog: Axolotl larva - In Salamander
This class is divided into three orders:
(A) Gymnophiona or Apoda
(B) Caudata or Urodela
(C) Anura or salientia
(a) Order - Gymnophiona Of' Apoda
Their body is worm like. These are primitive amphibians burrowing in nature.
Their body is limbless.
Skin is soft, and moist, with mucous glands; small scales (cycloid) are found on the skin.
Their eyes are covered by opaque skin. (Blind)
Middle ear and tympanic membrane a
Answered by
1
aves have envolved from mammals . they almost have same features. the difference between them is only that aves have wings but mammals don't. aver lay eggs but mammals don't. they both are warm blooded animals . they both have four chambered hearts
Similar questions