introduction to the vertebrata
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Introduction to the Vertebrata
And their relatives
1. Animals with a hollow dorsal nerve cord, notochord, and pharyngeal gill slits. 2. Brain encapsulated, or at least partially so, by a cartilaginous or bony cranium. Vertebrae, associated with or replace notochord. First duplication of genome (1R).3. Loss of vertebrae.4. Mineralized bone. Second duplication of the genome (2R).5. Head shield of dermal bone; bony scales.6. Paired spines or fins.7. Neurocranium encloses brain dorsally.8. Mouth formed by articulated jaws.9. Teeth erupt from dental lamina.10. Paired fin radials barely extend beyond body.11. Gills covered by an operculum.12. Pectoral and pelvic girdles anchored to vertebral column.13. Digits reduced to 5 or fewer; radius as long as the ulna. Operculum lost.14. Premaxilla less than 2/3 skull width.15. Egg with an outer amnion membrane.16. One temporal fenestra formed by the squamosal and jugal bones.17. Large post-temporal fenestra; suborbital foramen in palate.18. Two temporal fenestrae; upper one formed by the squamosal and postorbital bones.19. Trunk ribs single-headed, end of humerus robust.
General Animal Life Cycle
Vertebrate Development
Defining VertebratesThey posses the following characters at some point in their lives:• Pharyngial gill slits• Notochord• Hollow dorsal nerve cord• Vertebrae
Distribution of living groups of vertebrates
Myxinomorphithe hagfish
A cladogram based on Benton (2005), shows the agnathan taxa as a paraphyletic group. Myllokunmingida and Mixini, considered classes here, are sisters within a clade, the Myxinomorphi, that is sister to the Petromyzontomorphi (lampreys). Together, the lampreys and hagfishes form the Cyclostomata. Myllokunmingiida is in red because it has no extant members.
Hagfish
• The minimal vertebrate• Hagfish, cyclostomes without vertebrae
Hagfish Pacific hagfish feeding
Petromyzontomorphithe lampreys
A cladogram that illustrates the position of the two classes of the Petromyzontomorphi in the jawless fishes is based primarily on Benton (2005). However, Petromyzontida (the lampreys) are presented as sisters to the Euphaneropsids as proposed by Janvier (2008a). Here, they are shown as a sister group to the hagfish and basal within the Vertebrata in a clade called Cyclostomata (the round mouths). Euphaneropsida is in red because it has no living members.
Lampreys
ChondrichthyesSharks, Skates, Rays, & Chimeras
A cladogram of the gnathostome fishes according to Benton (2005). The two major clades of the Chondrichthyes: Euchondrocephali and Elasmobranchii both have extant taxa.
1) Jaws fused to cranium; 2) jaws not fused; 3) multiple, separate gill slits; 4) no anal fin
Chimeras
RatfishSpotted ratfish
ElasmobranchsSharks, Skates, & Rays
Great White Shark
Basking Shark
Eagle Ray
Spiny Dogfish Shark
Cladoselache
Osteichthyesthe bony fishes
A cladogram that illustrates the relative position of the Osteichthyes (Actinopterygii + Sarcopterygii) in the gnathostome fishes. 1. ray-finned fishes; 2. basal ray-fins; 3-4. remnants
of earlier radiations; 5. teleosts; 10. lobe-fins + tetrapods
Bony Fishesremnants of early radiations
BowfinLong-nosed Gar
Volga Sturgeon
Bichir
Bony Fishesremnants of early teleost groups
Arapaima Common Carp
Blue Catfish
Bony Fishteleosts
Atlantic Cod
Rainbow Trout
Basal teleosts, note separation of pectoral and pelvic fins
Cods are among the most primitive of the spiny-rayed fish, note that the pelvic fins have moved far forward
Bony Fisheshigher teleosts
Guppies
SargassumSeahorse
Long-ear Sunfish
African Jewel Cichlid
Mola
Blue-fin Tuna
Lobe-fin Fishes
AfricanLungfish
Australian Lungfish
Coelocanth
Batrachomorphathe amphibians
Frogs, Toads, & SalamandersStrawberry PoisonDart Frog Hellbender
African clawed frog
Axolotl
Mammaliaanimals with hair
• Hair• Single tooth-bearing
lower jaw bone• Teeth replaced one
time• Mammary glands• Teeth with
differentiation
Dimetrodon
Non-placental mammals
Platypus
Virginia Possum
Kangaroo
Placental mammals I
Tenrec
African elephant
Nine-banded armadillo
Three-toed sloth
Placental mammals II
Golden-crowned fruit bat
Mole
Przewalski’s horse
Least weasel
White-tailed deer
Blue whale
Placental mammals III
Aye-aye
Snow monkeys
Capybara
Cottontail rabbit
Anapsidaturtles
Scutosaurus
Turtles
Malamata
Sea turtle
Softshell turtle
Aldabra tortoise
Lepidosauromorphalizards & snakes
Plesiosaur
Diapsid skull
Lizards & Snakes
Iberian worm lizard
Glass lizard
Blue-tongued skink
Leopard gecko
Green tree iguana
Indian python
Spectacled cobra
LepidosauromorphaCrocs, Birds, & Dinosaurs
Archaeopteryx
Crocodilians
American alligator
Euparkeria, a stem archosaur from the mid-Triassic
Dinosaurs
Deinonichus, TheropodDiplodocus, Sauropod
Triceratops, CeratopsianCamptosaurus, Hadrosaur
Birds
• Basal clades (12 & 14)
• Waterbird assemblage (15)
• Owl-Cuckoo assemblage (16)
• Perching birds (17), including the songbirds (18)
Basal Clades
Turkey
Ostrich
Wood Duck
Waterbird Assemblage
Whooping Crane
Peregrine Falcon
Owl-Cuckoo Assemblage
Barn Owl
Cockatiel
Perching Bird AssemblagePileated Woodpecker
Scissor-tailed Flycatcher
Rook
Raggiana Bird-of-Paradise
House SparrowBlack-capped Chickadee
Barn Swallow
Galapagos Finch
Vertebrates
• OVER CLASSIFIED…
• Why?
Vertebrates
• OVER CLASSIFIED– Degree of difference between orders of birds
DOES NOT APPROACH that observed between orders of insects!!!
Vertebrates comprise a group within Chordates
– Hollow dorsal nerve cord– Notochord– Pharyngeal Gill Slits
• Other Chordates:– Cephalochordates
– Tunicates
Evo-Devo• Literally means evolution by means of changes
in development• Discovery of HOX genes in the 1980s• These are genes that regulate the on-off
switch for genes in development and determine timing
• Arranged in linear arrays that correspond to anterior-posterior axis
Major Events in the Evolution of the Vertebrates
• The evolution of jaws
Entelognathus (419 MYA), Zhu et al. 2013. Nature. 502:188-193. Earliest known fish with jaws. These were more similar to jaws of bony fishes that sharks
Major Events in the Evolution of the Vertebrates
• The evolution of a weight-bearing appendicular skeleton
Tiktaalik
Acanthostega
Major Events in the Evolution of the Vertebrates
• The evolution of the amniotic egg • This would be the point of transition between
amphibians and reptilesMoschops
Seymouria
Major Events in the Evolution of the Vertebrates
Archaeopteryx
Major Events in the Evolution of the Vertebrates
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