36
It can be suggested that such adaptations to saline environment are evidence for a
marine evolutionary origin of crocodiles (Rasmussen et al. 2011a , b ).
Interestingly, the estuarine crocodile C. porosus possesses one additional organ
for salt regulation – the cloaca. It was demonstrated (Kuchel and Franklin 2000 ) that
the function of the cloaca/lower intestine is highly plastic. “Plasticity of function
may be refl ected in the plasticity of morphology of the cloaca, as it was for the
lingual salt glands in C. porosus ” (Kuchel and Franklin 2000 ). Urodaeum is the part
of the cloaca into which the ureters and genital ducts empty, and, probably the primary
site for postrenal modifi cation of urine in this species (Kuchel and Franklin 2000 ).
Examination of its mucosal surface by scanning electron microscopy showed a plastic
response to environmental salinity. Thus, a possible increase in surface area in C. porosus
kept in hyperosmotic water compared with species from fresh water. However, the
renal/cloacal complex is responsible only for 2 % of the total Na effl ux in comparison
with 55 % of the lingual salt glands account. The urinary system in crocodile appears
to be the principal route for excretion also of potassium (Taplin 1985 ).
1.2.3.3 Class Aves (Birds)
Archaeopteryx lithographica , the feathered archaeornithine, arose in late Jurassic
(145 Ma), and is the earliest known bird today (Ostrom 1976 ; Ruben 1991 ).
“It possessed (at least) complete wing and tail plumage and a striking superfi cial
skeletal similarity to some carnivorous dinosaurs” (Ruben and Jones 2000 ). Another
ancient “bird-like” animal is the Ichthyornis (meaning “fi sh bird”, after its fi sh-like
vertebrae). The 95–85 Ma old fossil remains of these toothed seabirds from are
known from the chalks of Alberta, Alabama, Kansas, New Mexico (see for review
Clarke 2004 ). As proposed by Olson ( 1985 ), Ichthyornis has been scientifi cally
important from the view of bird evolution. As the fi rst discovered prehistoric bird
with exceptionally well preserved teeth, this animal was noted by Charles Darwin
because of its signifi cance during the early years of the theory of evolution. Today,
the fossilized remains of Ichthyornis are important as examples of the few birds of
Mesozoic origin known from more than a few specimens (Olson 1985 ).
It is suggested that that the basal lineages of modern birds originated deep within
the Cretaceous (Brown et al. 2008 ) as well as that avian endothermy is likely to
have been fully developed by about Late Cretaceous–Early Tertiary Periods
(Goedert 1989 ). The paleontological studies indicate that modern bird orders were
well defi ned by about 60 Ma (Feduccia 1996 ).
Because the oceans cover more than 3/4 of the Earth’s surface, many birds have
adapted to life over open water or along the coasts. Numerous species of birds
use aquatic niches for feeding. Especially seabirds gather all of their food at sea
where they spend most of their time (Enticott and Tipling 1997 ). Seabirds as a group
(Kennedy and Page 2002 ), are very successful (Ainley 1980 ). The populations
of seabirds are numbering in the hundreds of millions, however only 3 % of the
8,600 known bird species are seabirds. Furthermore, seabirds are impressive
examples of physiological plasticity. This makes seabirds among the most abundant
1 Introduction
It can be suggested that such adaptations to saline environment are evidence for a
marine evolutionary origin of crocodiles (Rasmussen et al. 2011a , b ).
Interestingly, the estuarine crocodile C. porosus possesses one additional organ
for salt regulation – the cloaca. It was demonstrated (Kuchel and Franklin 2000 ) that
the function of the cloaca/lower intestine is highly plastic. “Plasticity of function
may be refl ected in the plasticity of morphology of the cloaca, as it was for the
lingual salt glands in C. porosus ” (Kuchel and Franklin 2000 ). Urodaeum is the part
of the cloaca into which the ureters and genital ducts empty, and, probably the primary
site for postrenal modifi cation of urine in this species (Kuchel and Franklin 2000 ).
Examination of its mucosal surface by scanning electron microscopy showed a plastic
response to environmental salinity. Thus, a possible increase in surface area in C. porosus
kept in hyperosmotic water compared with species from fresh water. However, the
renal/cloacal complex is responsible only for 2 % of the total Na effl ux in comparison
with 55 % of the lingual salt glands account. The urinary system in crocodile appears
to be the principal route for excretion also of potassium (Taplin 1985 ).
1.2.3.3 Class Aves (Birds)
Archaeopteryx lithographica , the feathered archaeornithine, arose in late Jurassic
(145 Ma), and is the earliest known bird today (Ostrom 1976 ; Ruben 1991 ).
“It possessed (at least) complete wing and tail plumage and a striking superfi cial
skeletal similarity to some carnivorous dinosaurs” (Ruben and Jones 2000 ). Another
ancient “bird-like” animal is the Ichthyornis (meaning “fi sh bird”, after its fi sh-like
vertebrae). The 95–85 Ma old fossil remains of these toothed seabirds from are
known from the chalks of Alberta, Alabama, Kansas, New Mexico (see for review
Clarke 2004 ). As proposed by Olson ( 1985 ), Ichthyornis has been scientifi cally
important from the view of bird evolution. As the fi rst discovered prehistoric bird
with exceptionally well preserved teeth, this animal was noted by Charles Darwin
because of its signifi cance during the early years of the theory of evolution. Today,
the fossilized remains of Ichthyornis are important as examples of the few birds of
Mesozoic origin known from more than a few specimens (Olson 1985 ).
It is suggested that that the basal lineages of modern birds originated deep within
the Cretaceous (Brown et al. 2008 ) as well as that avian endothermy is likely to
have been fully developed by about Late Cretaceous–Early Tertiary Periods
(Goedert 1989 ). The paleontological studies indicate that modern bird orders were
well defi ned by about 60 Ma (Feduccia 1996 ).
Because the oceans cover more than 3/4 of the Earth’s surface, many birds have
adapted to life over open water or along the coasts. Numerous species of birds
use aquatic niches for feeding. Especially seabirds gather all of their food at sea
where they spend most of their time (Enticott and Tipling 1997 ). Seabirds as a group
(Kennedy and Page 2002 ), are very successful (Ainley 1980 ). The populations
of seabirds are numbering in the hundreds of millions, however only 3 % of the
8,600 known bird species are seabirds. Furthermore, seabirds are impressive
examples of physiological plasticity. This makes seabirds among the most abundant
1 Introduction