The Deuterostomes and the rise of the Vertebrates: from Echinoderms to Man

Transcription

1 The Deuterostomes and the rise of the Vertebrates: from Echinoderms to Man 1

2 The Deuterostomes Calcarea and Silicea Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia 2

3 The Ancestral Deuterostome Bilateral Symmetry Radial Cleavage Coelomate Internal Skeleton 3

4 Echinoderms are the Current most Basal Deuterostomes Bilateral symmetry is the ancestral condition. Echinoderms evolved unique pentaradial symmetry; other deuterostomes retained bilateral symmetry. Echinoderms show their ancestral condition in their development 4

5 The Anatomy of a Sea-star 5

6 Major Echinoderm Groups A Sea-Lily (Crinoids) ים - חבצלת Sea-Urchins ים - נחשון Brittle-Star Sea-Star Sea Cucumber 6

7 Hemichordates Hemichordates (acorn worms and pterobranchs) have a three-part body plan proboscis, collar, and trunk. 7

8 The Worm and the Proboscis An Acorn Worm 8

9 The Chordates All chordates share a set of derived characters Some species have some of these traits only during embryonic development Four key characters of chordates: Notochord Dorsal, hollow nerve cord Pharyngeal slits or clefts Muscular, post-anal tail Chordates 9

10 Chordates Craniates Vertebrates Gnathostomes Osteichthyans Lobe-fins Tetrapods Amniotes The Chordate Evolution Tree Echinodermata (sister group to chordates) ANCESTRAL DEUTERO- STOME Notochord Cephalochordata (lancelets) Urochordata (tunicates) Common ancestor of chordates Head Myxini (hagfishes) Petromyzontida (lampreys) Vertebral column Chondrichthyes (sharks, rays, chimaeras) Jaws, mineralized skeleton Lungs or lung derivatives Lobed fins Actinopterygii (ray-finned fishes) Actinistia (coelacanths) Dipnoi (lungfishes) Amphibia (frogs, salamanders) Legs Amniotic egg Milk Reptilia (turtles, snakes, crocodiles, birds) Mammalia (mammals) 10

11 The Cephalochordates (Lancelets) Cirri 2 cm Mouth Pharyngeal slits Atrium Notochord Dorsal, hollow nerve cord Digestive tract Atriopore Segmental muscles Anus Tail Sp. Branchiostoma 11

12 The Tunicates and the Notochord 12

13 The Urochordates (Tunicates) An adult tunicate Incurrent siphon to mouth Excurrent siphon Atrium Pharynx with slits Tunic Water flow Excurrent siphon Anus Intestine Esophagus Stomach Dorsal, hollow nerve cord Incurrent siphon Excurrent siphon Notochord Atrium Pharynx with slits A tunicate larva Tail Muscle segments Intestine Stomach 13

14 Get a head the Craniates The origin of a head opened up a completely new way of feeding for chordates: active predation Craniates have two clusters of Hox genes; lancelets and tunicates have only one cluster One feature unique to craniates is the neural crest, a collection of cells near the dorsal margins of the closing neural tube in an embryo Neural crest cells give rise to a variety of structures, including some of the bones and cartilage of the skull 14

15 The Hagfish A Simple Craniate 15

16 Finally The Vertebrates! Vertebrate characteristics: Rigid internal skeleton supported by the vertebral column. Anterior skull with a large brain. Internal organs suspended in a coelom. Well-developed circulatory system with a heart. 16

17 The Lamprey A jawless Vertebrate 17

18 Jaws The Gnathostomes 0.5 m A placoderm 18

19 Jaw Evolution 19

20 Fish- Chondrichthyans (Cartilage) Skate Ratfish 20

21 Ray-Finned Fish Brain Spinal cord Swim bladder Dorsal fin Adipose fin (characteristic of trout) Caudal fin Nostril Cut edge of operculum Gills Kidney Heart Liver Stomach Intestine Gonad Pelvic fin Anus Urinary bladder Lateral line Anal fin 21

22 The Coelocanths Lobe Finned Fish 22

23 Lungfish A step towards Life on Land 23

24 The Tetrapods - Amphibians 24

25 Amphibian Groups Order Apoda Order Anura Order Urodela Mud puppy Order Urodela 25

26 Life on Land the Amniotes 26

27 The Amniote Clades Diapsids Archosaurs X X X? Synapsids 27

28 The Mammals Characteristics of mammals: Hair Mammary glands Sweat glands Large brain (compared to other vertebrates Small mammals coexisted with dinosaurs for millions of years. Mammals increased in size and number after the extinction of dinosaurs 28

29 Mammalian Groups - Monotremes Echidna Platipus 29

30 Mammalian Groups - Marsupials 30

31 Mammalian Groups - Eutherians 31

32 The Primate Order 32

33 Emergence of the Hominins and Man 33

34 Millions of years ago Hominin Evolution and Brain Size Paranthropus boisei Paranthropus robustus Homo ergaster Homo neanderthalensis? Homo sapien s Australopithecus africanus Australopithecus anamensis Kenyanthropus platyops Australopithecus garhi Homo rudolfensis Homo habilis Homo erectus Ardipithecus ramidus Australopithecus afarensis Orrorin tugenensis Sahelanthropus tchadensis 34