All About Archaeopteryx

rape_donkeys

| ^ | A = Archaeopteryx | | | ___________________ T | | | i | | MODERN BIRDS | m | __ __ __ __ __| | e | | |___________________| | | FOSSIL | | __| BIRDS | | | A|__ __ __ __ __ __| | |___| |______________________________________________ "reptile" "bird" --- Morphology --> 1 = present; * = present in some; ? = possibly present; x = absent Dinosaurs Archae Birds1 * 1 12 x 1 13 * 1 14 * 1 15 x x 16 x x 17 * x 18 * 1 x9 1 1 x10 1 1 x11 1 1 x12 1 1 x13 1 1 x14 1 1 x15 1 1 x16 6 6 11-2317 1 1 x18 1 1 *19 1 1 x20 1 1 x21 1 1 x22 1 1 x23 1 1 xChicken enbryo Angle ilium-pubis Adults with same angle 7.0 days 45 degrees Archaeopteryx 7.3 days 35 degrees Kiwi 8.0 days 30 degrees Ostrich Hatching 5 degrees Modern chickenThe angle between the ilium and the pubis bones in the pelvis of modern Ratites is intermediate between Archaeopteryx and modern birds, as would be expected if:A) Modern birds are descended from reptile-like ancesters similar to ArchaeopteryxB) Ratites are neotenous descendents of flying birds, in which development has been halted prematurely. _____________________________ | | | |RATITES| MODERN BIRDS | |________| | |_____________________| ________________________________________________ "reptile" "bird" --- Morphology --> Adduction Abduction /( ) | | | | | | | | ( )/i.e. the wing can be drawn up over the back (try it and see how difficult it is). This full range of movement is important in allowing modern birds to power fly. It turns out that the shoulder joint of Archae appears to be intermediate in orientation between some coelurosaurs (theropod dinosaurs e.g. Deinonychus) and birds (Jenkins 1993) - just as one would expect from a transitional form. However, whilst the shoulder joint provided a substantial degree of arm (wing) elevation, it is not sufficient to allow full abduction as in modern birds. Thus the shoulder joint of Archae does not appear to allow the full range of movement needed for power flying.

Terry_Clubbup

|

^ | A = Archaeopteryx

| |

| ___________________

T | | |

i | | MODERN BIRDS |

m | __ __ __ __ __| |

e | | |___________________|

| | FOSSIL |

| __| BIRDS |

| | A|__ __ __ __ __ __|

| |___|

|______________________________________________

"reptile" "bird"



<--- Morphology -->





1 = present; * = present in some; ? = possibly present; x = absent

Dinosaurs Archae Birds

1 * 1 1

2 x 1 1

3 * 1 1

4 * 1 1

5 x x 1

6 x x 1

7 * x 1

8 * 1 x

9 1 1 x

10 1 1 x

11 1 1 x

12 1 1 x

13 1 1 x

14 1 1 x

15 1 1 x

16 6 6 11-23

17 1 1 x

18 1 1 *

19 1 1 x

20 1 1 x

21 1 1 x

22 1 1 x

23 1 1 x



Chicken enbryo Angle ilium-pubis Adults with same angle



7.0 days 45 degrees Archaeopteryx

7.3 days 35 degrees Kiwi

8.0 days 30 degrees Ostrich

Hatching <5 degrees Modern chicken[/b]





The angle between the ilium and the pubis bones in the pelvis of modern Ratites is intermediate between Archaeopteryx and modern birds, as would be expected if:



A) Modern birds are descended from reptile-like ancesters similar to Archaeopteryx



B) Ratites are neotenous descendents of flying birds, in which development has been halted prematurely.







_____________________________

| | |

|RATITES| MODERN BIRDS |

|________| |

|_____________________|



________________________________________________

"reptile" "bird"



<--- Morphology -->







Adduction Abduction



/( ) | |

| | | |

| | ( )/



i.e. the wing can be drawn up over the back (try it and see how difficult it is). This full range of movement is important in allowing modern birds to power fly. It turns out that the shoulder joint of Archae appears to be intermediate in orientation between some coelurosaurs (theropod dinosaurs e.g. Deinonychus) and birds (Jenkins 1993) - just as one would expect from a transitional form. However, whilst the shoulder joint provided a substantial degree of arm (wing) elevation, it is not sufficient to allow full abduction as in modern birds. Thus the shoulder joint of Archae does not appear to allow the full range of movement needed for power flying.

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ADVANCED D&D MATHEMATICS

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