45
than fl anges. Some burrow-nesting seabirds also retain egg teeth for a long time.
This reinforces the idea that egg-tooth refl ectance may have evolved independently
in several phylogenetic groups in which parents must fi nd nestlings in the dark,”
(Wiebe 2010 ).
Gular Pouches
It is well known that such seabirds as pelicans dive into water for fi sh from altitudes
of 9–16 m (Allen 1923 ). They also attain speeds of up to 18 m/s before water impact
(Johnsgard 1993 ). Pelican’s gular pouches are highly distensible constructs. They
can hold up to 11 L of water (Schreiber et al. 1975 ). “When the mandibles bow (from
a resting position of about 5 cm apart to over 15 cm apart) the opening created is
approximately 500 cm
2
. This bowing, termed streptognathism , is well-developed in
birds that are able to swallow large objects,” (Meyers and Myers 2005 ). Another type
of joint in which bones are joined by connective tissue has been observed in gulls
and other species, including pelicans. This is known as “ syndesmosis ” (Judin 1961 ).
Recently, Meyers and Meyers ( 2005 ) investigated the bending of the Brown
Pelican ( Pelecanus occidentalis ) lower jaw. They showed “that both mineral content
and bone shape contribute to the high degree of bowing observed when this species
dives into the water for food,” (Meyers and Myers 2005 ). The bones have a mineral
content of about 52 % and play crucial role within the syndesmotic joint. This joint
permits these bones to move relative to one another, much like a leaf-spring functions (Buhler 1981 ).
Bones
Hierarchically structured bones of vertebrates distinguish in their details. Both
ectothermy and endothermy play here very important role. Thus, so called lamellarzonal bone of ectothermic extant amphibians and most reptiles “has a layered
appearance, within which incremental growth lines are occasionally recognized; it
is also poorly vascularized,” (Ruben et al. 1998 ). Endothermic animals like birds,
mammals, and dinosaurs, mostly possess well vascularized fi bro-lamellar bone (Reid
1997 ; Margerie de 2002 ). As discussed by Ruben and co-authors: “fi bro-lamellar
bone is often held to be correlated with high growth rate that requires rapid deposition of calcium salts. Such rapid growth is supposedly possible only in systems with
high metabolic rates associated with endothermy,” (Ruben et al. 1998 ). Recently, it
was proposed (Simons and O’Connor 2012 ) that laminarity is “an adaptation for
resisting torsional loading. This may be explained by overall wing shape: while
dynamic soaring birds have long slender wings, fl appers and static soaring birds
have broader wings with a larger wing chord that would necessarily impart a higher
torsional moment on the feather-bearing bones,” (Simons and O’Connor 2012 ).
We can analyses the bone as construct that represents a balance between hard
tissue economy and fl exural strength (see for review McGowan 1999 ; Currey 2003 )
(see also Sect. 3.1 ). From this point of view, the evolutionary expediency of development of hollow, tubular structures within tetrapod limb bones is not surprizing.
1.2 Part I: Biomaterials of Vertebrate Origin. An Overview
than fl anges. Some burrow-nesting seabirds also retain egg teeth for a long time.
This reinforces the idea that egg-tooth refl ectance may have evolved independently
in several phylogenetic groups in which parents must fi nd nestlings in the dark,”
(Wiebe 2010 ).
Gular Pouches
It is well known that such seabirds as pelicans dive into water for fi sh from altitudes
of 9–16 m (Allen 1923 ). They also attain speeds of up to 18 m/s before water impact
(Johnsgard 1993 ). Pelican’s gular pouches are highly distensible constructs. They
can hold up to 11 L of water (Schreiber et al. 1975 ). “When the mandibles bow (from
a resting position of about 5 cm apart to over 15 cm apart) the opening created is
approximately 500 cm
2
. This bowing, termed streptognathism , is well-developed in
birds that are able to swallow large objects,” (Meyers and Myers 2005 ). Another type
of joint in which bones are joined by connective tissue has been observed in gulls
and other species, including pelicans. This is known as “ syndesmosis ” (Judin 1961 ).
Recently, Meyers and Meyers ( 2005 ) investigated the bending of the Brown
Pelican ( Pelecanus occidentalis ) lower jaw. They showed “that both mineral content
and bone shape contribute to the high degree of bowing observed when this species
dives into the water for food,” (Meyers and Myers 2005 ). The bones have a mineral
content of about 52 % and play crucial role within the syndesmotic joint. This joint
permits these bones to move relative to one another, much like a leaf-spring functions (Buhler 1981 ).
Bones
Hierarchically structured bones of vertebrates distinguish in their details. Both
ectothermy and endothermy play here very important role. Thus, so called lamellarzonal bone of ectothermic extant amphibians and most reptiles “has a layered
appearance, within which incremental growth lines are occasionally recognized; it
is also poorly vascularized,” (Ruben et al. 1998 ). Endothermic animals like birds,
mammals, and dinosaurs, mostly possess well vascularized fi bro-lamellar bone (Reid
1997 ; Margerie de 2002 ). As discussed by Ruben and co-authors: “fi bro-lamellar
bone is often held to be correlated with high growth rate that requires rapid deposition of calcium salts. Such rapid growth is supposedly possible only in systems with
high metabolic rates associated with endothermy,” (Ruben et al. 1998 ). Recently, it
was proposed (Simons and O’Connor 2012 ) that laminarity is “an adaptation for
resisting torsional loading. This may be explained by overall wing shape: while
dynamic soaring birds have long slender wings, fl appers and static soaring birds
have broader wings with a larger wing chord that would necessarily impart a higher
torsional moment on the feather-bearing bones,” (Simons and O’Connor 2012 ).
We can analyses the bone as construct that represents a balance between hard
tissue economy and fl exural strength (see for review McGowan 1999 ; Currey 2003 )
(see also Sect. 3.1 ). From this point of view, the evolutionary expediency of development of hollow, tubular structures within tetrapod limb bones is not surprizing.
1.2 Part I: Biomaterials of Vertebrate Origin. An Overview