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BIODIVERSITY SEMESTER TWO NOTES
BEFORE THE BACKBONE
Aims:
- The diversity of echinoderms and hemichordates
- Chordates: general features, urochordates and cephalochordates
Protostomes
- so far, all multicellular animals covered in this modules were protostomes
- protostomes are characterised by a primary body opening during embryo formation
(Blastopore) which developed into the mouth, whereas the anus forms secondarily
Deuterostomes
- The primary body opeing develops into the anus and the mouth is a secondary
opening (deutero = second, stoma = mouth)
- In their basic body plan, deuterostomes also have a dorsal nerval system and a
ventral digestive system (whereas for example arthropods have ventral nerves)
The Main Classifications within the Deuterostomes
- Three main phyla:
1
...
Hemichordata
3
...
Urochordata
ii
...
Vertebrata

Phylum Echinodermata
- Evolved from bilaterally symmetric to pentaradially symmetric animals
- Have ciliated larvae (a shared feature of deuterostomes)
- Have calcified internal skeleton (compare vertebrates)
- Their coelom is divided into three parts: protocoel, mesocoel and metacoel
- Lack of excretory organs, no circulatory system and heart (haemolymph circulating
through body), no brain (nerval system without concentrations)
- Purely marine, five major groups
1
...
Crinoidea
3
...
Ophiuroidea
5
...
Notochord  Dorsal stiffening rod, giving the group the name chordates
2
...
Segmented, Muscular, Postanal tail  extending beyond the gut region
4
...
g
...
g
...
Links between existing
tunicates and cephalochordates are difficult to establish (extinct common ancestors)
but would be very important for an understanding of the evolution of vertebrates
- Pikaia gracilens is a fossil from the Burgess Shale (505 million years old, Canada);
is possessed myomeres and notochord, and could be a cephalochordate or another
sister group to vertebrates
- Further fossils of early chordates have also been found in early Cambrian deposits
(520 million years) in Southern China
...

- not all vertebrae are bony and some vertebrates (hagfishes) entirely lack vertebrae
- A uniquely derived feature of all vertebrates is to have a skull (Cranium, bony or
cartilaginous structure surrounding the brain)
...
g
...

- The forebrain (telencephalon, area of higher processing) is absent in Amphioxus,
whereas midbrain and hindbrain find their homologous structures
- All vertebrates show a duplication in the Hox gene complex (a set of genes
regulating the expression of other genes to determine the body plan): amphioxus has
one set, jawless fishes have two sets, jawed vertebrates have >four sets
Three Germ Layers and their Functions in Vertebrates
1
...
The Endoderm forms the digestive tract (also liver and pancreas), and lungs
3
...
It splits
to form the coelom (body cavity containing internal organs)
...
The innermost integument (Hypodermis) overlays
muscles and bones (fat storage and small striated muscles)
- Keratin is a ectoderm protein unique for vertebrates
...
g
...
It mainly consists of plasma
(Liquid) and blood cells
- Arteries carry blood away from the heart, veins return blood to the heart
- Capillaries connect arteries and vein and are the site of exchange between blood
and tissue
- The heart contains three sequential chambers (sinus venosus, atrium, ventricles)
Nerval System and Sensory Organs
- Dual type of nervous system: Somatic (voluntary, derived from somites) and
visceral (involuntary)
- 10 pairs of cranial nerves (I-X, e
...
II is the optic nerve) directly emerging from the
brain
- All vertebrates possess a forebrain (smell), midbrain (vision) and hindbrain
(hearing)
- All vertebrates possess a retina with cones and rods
Excretory and Reproductive System
- Excretory organs are mesoderm derivates
- Kidneys dispose of waste products (in addition to gills and skin) through the ureter
...
Male gonads (testes) produce sperm in semiferous tubes
- In male mammals, the testes become externally placed
...
Ostracoderms are likely a polyphyletic group,
placed close to the extant jawless fishes (lampreys and hagfishes)
- No evidence for a skeleton or jaw, but armoured with trunk scales sometimes
forming a carapace (ostraco = shell, derm = skin)
...
They seem to be tooth-like elements of eel-like
vertebrates (Conodonts)
- Their lack of a well-mineralised skeleton might provide evidence for its origin from
tooth-like ossifications
Extant Early Craniates: The Hagfishes (Myxinoidea)
- About 40 species known (Marine); complete lack of vertebrae
- Predators feeding on worms in muddy substrates
- Slimy mucus covers skin when attacked
- Sex ratios 1:100 in favour of females
The Lampreys (Petromyzontoidea)
- About 40 species
- Cartilaginous vertebral structures
- One nostril, conspicuous oral hood to form a circular mouth (“cyclostomes”)
- Most species are ectoparasites on other fishes, on which they feed
...
The
original function might have been improved gill ventilation
- Teeth are skin derivates (otodonts!), and teeth must have evolved after the jaw was
in place
...
They comprise all classes of vertebrates except fishes (i
...
all
primarily terrestrial vertebrates)
- Tetrapods are descendants of lobe-finned fishes
- It was long assumed that the coelacanth Latimeria is the closest living relative of all
tetrapods
...
Early
fossils combine features from frogs and salamanders
- The earliest known fossil frogs were long seen as being from Madagascar (no
jumping abilities, 250 million years old)
- In 2008, a 290 million years old frog was found in texas, now being the oldest known
modern amphibian
- (in the 17th century, fossils of a large Miocene Salamander we interpreted by
naturalist J
...
Anurans  frogs and toads
2
...
Caecilians  apodans, “naked snakes”
- Three groups lack clear synapomorphies (shared derived characters) and their
evolutionary history is difficult to disentangle; combined palaeontological,
morphological and genetic evidence now supports scenario A

-

Caecilians (Apodans) – the Least Known Vertebrate order
- ~180 species
- Subterranean, terrestrial life (there are exceptions!) requires specialised reproduction
- Internal fertilisations, egg-laying or viviparous (dispite large young)
- In viviparous species, energy for growth is supplied through secretions from walls of
oviducts (“uterine milk”), combination with specialised fetal dentitions for scraping
oviductal walls
- Early stages possess fetal gills for gas exchange across oviduct walls, potentially
also exchange of metabolic waste
- Some species also feed on their mothers skin after birth, as an analogy to lactation
Morphology and Ecology of Caecilians
- Large number of vertebrae (up to 285)
...
Skull covered in dermal bones
- Prey is captured with jaws (no protrusible tongue)
...
The tentacle is a sensory organ unique in
vertebrates that can be moved with muscles originally used for eye movement
Distribution
- Purely tropical, but disjointed: Central America, Amazonia & Guyana shields, West
and East Africa, Seychelles, South Asia
Urodeles (Newts and Salamanders)
- ~450 species
- Adults with a tail
- Aquatic larvae have external, feather-like gills
...
g
...

Anurans (Frogs and Toads)
- The most diverse group of amphibians (~7000 species)
- Two main groups
1
...
Neobatrachia  modern groups
- Lots of uncertainties (and ongoing taxonomic changes) about the phylogeny of even
common species
- “frog” and “toad” are distinctions without a scientific basis
Biodiversity – Examples of Recent Discoveries
- Discovered in 2013: the European common toad (Bufo bufo) is not a single species
- Discovered in 2014: a new frog family from West Africa
Life Characteristics
- Adults without a tail

-

Aquatic larvae (tadpoles) with internal gills, hind legs develop before front legs,
herbivores
- External fertilisation of egg clutches
...
Some
species have protractable tongue
- Vocal (but also other) communication – largely communicate acoustically
- General trend towards miniature across lineages
Body Plan and Modes of Locomotion
- 1modern frogs are animals built for jumping, whereas the ancestors of frogs were
more salamander-like
- Elongated muscular hind limbs create the force for jumping, whereas the pectoral
girdle and front legs absorb the shock when landing
- Low number of vertebrae, fused limb bones, reduced skull elements and long
pelvic girdle (urostyle: fused tail vertebrae) with hind limbs articulated close together
support the jumping ability
- However, in addition to jumping frogs can walk, hop, burrow, climb, swim and glide…
Distribution
- Almost worldwide (except Arctic regions, Sahara desert and New Zealand South
Island)
Anurans have a very high Reproductive Diversity – example Amazon

DIVERSITY AND EVOLUTION OF AMNIOTES, “REPTILES” AND BIRDS
A Brief Recap…
- Tetra = 4
- Pod = leg/limb
- Tetrapoda is a Clade of vetebrates characterised by the possession of four limbs
with digits
- There are two clades of living tetrapods:
1
...
Amniota or Amniotes
- There are also many other fossil tetrapod groups besides Lissamphibia and
1amniota, but we don’t have time to discuss them
AMNIOTE EGG
- The “anamniote” egg of lissamphibians are relatively simple:
o Outer jelly layers  limited protection against dehydration and predators
o Single membrane encloses the embryo  gasses freely diffuse across this
membrane
Amphibian-type (“anamniote”) Egg has Major Limitations
- Vulnerable to dehydration
o Usually has to be laid in fresh water; if laid on land, they must be protected
from dehydration (e
...
by foam nests)
- Adult lissamphibians also vulnerable to dehydration due to semi-permeable skin
o No fully marine and few desert lissamphibians
Series of Additional Extra-Embryonic Membranes
- Amnion  encloses the embryo in liquid
(amniotic fluid), gives amniotes their name
- Chorion and allantois  facilitate gas
exchange (oxygen into the egg and carbon dioxide
out of the egg)
- Egg shell  originallt leathery, as in lizards,
crocs, turtles monotremes; mineralised in birds
- Collectively, these membranes form an
enclosed, protective environemnt (a “private pond”)
for the developing embryo
- These membranes are still present in
amniotes that have evolved live birth (viviparity)
o In placental mammals (e
...
humans),
an amniotic sac still surrounds the embryo, and the
placenta is formed from the chorion and allantois
- Because of these extra-embryonic
membranes, amniotes can lay their eggs in much
drier environments
- Amniotes also characterised by “waterproof” skin, including scales, feathers or
hairs  much less vulnerable to dehydration than lissamphibians
Terrestrial Adaptations
- The terrestrial adaptation of amniotes have made them evolutionarily very successful
- >25,000 living species (versus ~7500 living lissamphibian species)
- Many, many more fossil species and extinct groups

Amniote Phylogeny
- A good (but not perfect) guide to the evolutionary relationships of amniotes is the
structure of the back part of the skull
o Presence or absence of holes called temporal fenestrae
- Four basic patterns:

-

-

-

all living amniotes have either anapsid, synapsid or diapsid skulls:
o Turtles = anapsid
o Mammals = synapsid
o Crocodiles, lizards, snakes, birds etc
...
g
...
g
...
g
...
)
- The reason “reptilia” is not used is because
Sauropsida is clearly monophyletic
- “traditional definition of Reptilia (excludes birds) is
paraphyletic
- Modern classifications only recognise
monophyletic groups (clades)
- Either redefine Reptilia so that it includes e
...

birds or use a clade name that is less ambiguous
and specifically included birds  Sauropsida

Diversity of Diapsida

Lepidosauria
- >9,000 living species
- Today there are:
o Two species of tuatara (sphenodon) which
survive on small islands of the coast of new
Zealand; individuals may live >100 years
o Squamata - >9,000 species (snakes, lizards
etc
...

Megalania Prisca (or Varanus Priscus) is a giant relative of the komodo dragon
that survived in Australia until 50,000 years ago
o up to 7m long and >300kg in weight
o almost certainly overlapped with humans

Snakes (Serpentes)
- snakes are very specialised squamates
- skull very lightly built, with flexible joints between most bones – allows swallowing of
large prey
- body very elongate - >200 vertebrae
- because of long, thin body usually only right lung is functional (left very small or
absent) and Kidneys “staggered”
- very successful group - >3,000 living species, ranging from 10cm to ~7m
- Two major theories for origin of snakes:
1
...
They evolved from giant extinct marine lizards called mosasaurs
- Current evidence seems to support the burrowing hypothesis
o Only known fossil snake with four legs, Tetrapodophis (~108 million years
old) from brazil, was probably a burrower
- Titanoboa – largest known fossil snake
o 60 million years old, Colombia
o ~13m long
o >1 tonne in weight
Archosauria
- Two major living clades of archosaurs
o Crocodylia – crocodiles, aligators and gharials (24 living species)
o Aves – birds (>10,000 living species)
- Turtles may also belong to this group
- There are many fossil groups that are either “crocodile-line” archosaurs or “bird-line”
archosaurs

Crocodylia and other “crocodilian-line” archosaurs
- Crocodylia – 24 living species – all relatively large, semi aquatic predators
- There are many fossil “crocodile-line” archosaurs
- Many of these appear to have been very active, terrestrial animals with erect stances
(some were bipedal)
o May have been endothermic “warm blooded”
- Modern crocodilians are ectothermic “cold blooded” – may be secondary

o
o

Modern crocodilians are not “living fossils” – they are highly specialised semiaquatic ambush predators
Other “crocodile-line” archosaurs show a wide range of adaptations and
lifestyles/ecologies

“Bird-line” Archosaurs
- There are many “bird-line” archosaurs – most are extinct
- Two major groups are:
o Pterosauria – pterosaurs
o Dinosauria – dinosaurs (including living birds)
Pterosauria
- One of only three vertebrate clades that evolved true, powered flight (together with
bats and birds)
- Two key points:
o Pterosaurs are not dinosaurs, although they are not “bird-line” archosaurs
o “pterodactyls” refer to a subgroup of pterosaurs – Pterosauria refers to the
group as a whole
- First known from the late Triassic (230 million years ago)
- Survived until the K-Pg mass extinction (66 million years ago)
- Wing formed by a membrane supported by an elongate fourth digit
- Presumably endothermic (“warm blooded”) – flight energetically very demanding
o At least some were covered by “fuzz” – presumably insulation
- Earliest forms relatively small (wingspan ~1m)
- Later forms include the largest flying animal ever: Quetzalcoatlus northropi
(wingspan ~10m)
Dinosauria
- Many synapomorphies of Dinosauria related to an upright, bipedal stance
- Earliest dinosaurs probably small, bipedal predators (like early form Eoraptor)
- Two major subclades within Dinosauria that differ in the structure of the pelvis:
o Saurischia (“lizard-hipped” dinosaurs) – pubis bone slopes forward
o Ornithischia (“bird-hipped” dinosaurs) – pubis bone slopes backwards
Ornithischia
- Herbivorous
- Include:
o Horned dinosaurs (ceratopsians) e
...
Triceratops
o Armoured dinosaurs (stegosaurs and ankylosaurs) e
...
Stegosaurus and
Ankylosaurus
o Duck-billed dinosaurs (hadrosaurs) e
...
Hadrosaurus
Saurischia
- Two major groups of Saurischians – Sauropodomorpha and Theropoda
Sauropodomorpha:
- Generally large-bodied, long-necked and herbivourous
- Largest >30m long, >50 tonnes in weight
Theropoda:
- Bipedal
- Most were carnivorous
- Largest include Tyrannosaurus, Giganotosaurus and Spinosaurus – probably >5
tonnes and >10m long
- Included birds and whole range of more-or-less bird-like relatives
- Most theropods probably had some kind of feathery covering

Origin Of Birds
- Compared to their closest living relatives (crocodylians), birds show a large number
of anatomical specialisations
- Fossil records show that many of these features evolved before the origin of birds
- There are now many “intermediate” taxa within Dinosauria that show various
combinations of birs-like features
- The discovery of “feathered dinosaurs” has been particularly important
- “Protofeathers” now known from saurischians and ornithischians
o Likely originally evolved for insulation – indication of endothermy?
o Flight feathers evolved much later
- Lineage of theropod dinosaurs that gave rise to birds characterised by sustained
evolution of small bosy size over 50 million years
- Several major theories for evolution of flight in birds
o “ground up” – wings initially evolved for stabilisation when running after prey
or to help catch insects?
o “trees down” – wings evolved for gliding in tree tops
o Wing assisted incline running (WAIR) – wing beat allows running up steep
slopes e
...
tree trunks
- “trees down” model perhaps more plausible given the existence of small gliding
theropods e
...
Microraptor
- Archaeopteryx often reffered to as the oldest tru bird – 150 million years old,
(Germany)
- However older birds are now known - ~160 million years old from China – e
...

Achiornis
- Study of structures called melanosomes preserved in fossils gives insight into the
probable colour of these animals when alive
- Early birds e
...
Anchiornis and Archaopeteryx retain plesiomorphic features lost in
moder birds:
o Long tail (rather than pygostyle – the “parsons nose”)
o Teeth
o No beak
o Claws on forelimb
Modern Birds
- Modern birds (Aves) comprises >10,000 living species
- Two major groups:
o Palaeognaths - ~50 living species
 Included the flightless ratites (ostriches, cassowaries, rheas, kiwis,
moas etc
...
g
...
e
...
e
...

 Sauropterygia – plesiosaurs etc
...
Origin of mammals
2
...
Diversity of Mesozoic mammals
4
...
5m long, >300kg
- Hebivorous
Dicynodonts
- Diverse radiation of herbivourous synapsida
- 260 to 200 million years ago
- Some capable of burrowing
- Immediately after the end-permian extinction, in the earliest Triassic, 95% of tetrapod
fossils are of the dicynodont Lystrosaurus
Gorgonopsians
- Large carnivores – largest have body ~3
...
Need to maintain constant body temperature regardless of the external
environment (homeothermy)
- 2
...
g
...
g
...
g
...
e
...

Mammal teeth have very complex terminology
o Every “bump” (cusp) and crest has its own name
o

-

ORIGIN OF MODERN MAMMALS
Three major groups of Modern Mammals:
- Placentals (placentalia)  >4,500 species
- Marsupials (marsupialia)  >300 species
- Monotremes (monotremata)  4 species
Origin of Modern Mammals
- Among the three groups of modern mammals, monotremes are the first to split off
o Recent molecular clock analyses suggest this split occurred 200-250 MYA i
...

about the same time as the oldest true mammals
o The split between placentals and marsupials occurred 150-190 million
years ago
o So the three groups of living mammals (placentals, marsupials and
monotremes) diverged from each other during the Mesozoic, long before
the K-Pg boundary

DIVERSITY OF MODER MAMMALS
BRIEF RECAP:
Amniote phylogeny:
- Current evidence suggests a basal split between
o Synapsida
o Sauropsida (which includes Parareptilia and Diapsida)
- Mammals are they only living synapsids
Origin of mammalia:
- The oldest and most primitive true mammals are about 200-220 million years old
Diversity and Distribution of Modern Mammals
Three major clades:
- MONOTREMATA (Monotremes)  5 describes species =0
...
7-2
...
)
- Range  throughout australia and parts of New Guinea (short-beaked echidna);
New guinea (Zaglossus spp
...
)
- Diet  mainly ants and termites (Ta); mainly earthworms (Z spp
...
) have ~2,000 electroreceptors in beak
- Short beaked echidna (Tachyglossus aculeatus) has ~400
o Suspected that electroreception is used by echidnas in feeding
Monotremes have a Venomus Spur on Hindlimb
- Spur is well-developed in male platypuses only
- Used to be though to be unique to monotremes but now known in several Mesozoic
mammal groups
o Possibly lost in ancestor of marsupials and placentals
Monotremes Lack Functional Teeth
- Big problems given the emphasis of teeth in understanding mammal fossil record and
evolution
Modern Monotreme are NOT “living fossils”
- They are a mix of:
o Plesiomorphic (primitive) features  e
...
egg-laying, cloaca
o Apomorphoc (specialised) features  e
...
electroreception, absence of
functional teeth
Taken as whole animals, they are not good models for the last common
ancestor of modern mammals
Monotreme Fossil Record
- Oldest true monotremes are ~100-120 million years old from Australia
- One fossil monotreme (Monotrematum) is know from a ~63 million year old fossil site
in South America
- Obdurodon tharalkooschild: “giant” (>1m body length) fossil platypus with teeth
known from 5-15 million year old fossil site in Australia
- Giant fossil echidnas also known – largest >30kg and died out ~50,000 years ago
MARSUPIALS

Marsupial reproductive mode
- Marsupials characterised by short gestation period
o Shortest = 12-13 days
o Longest = 37 days
- Newborn marsupials very poorly-developed
- Marsupials are not born in the pouch (and not all marsupials have a pouch)
o They crawl from the vagina into the puch (if present)  forelimbs relatively
well-developed
o Attach to nipple and remain there feeding on milk for several months
Oldest Marsupial Relative
- Oldest marsupial relative is ~125 million years old – Sinodelphys from China
Biogeography of marsupials and marsupial relatives
- Ancestors of marsupials evolved in northern hemisphere (e
...
Sinodelphys)
- ~80-65 million years ago, some marsupial relatives moved from North America to
South America along temporary land connection or island chain
...
Hedgehogs, moles, tenrecs
- “Ungulates”  “hoofed mammals”, hippopotamus, elephant, zebra, camel etc
...
g
...
g
...

- “fully aquatic forms”  whales and sea cows (sirenians), both which give birth in
the water
- “edentates”  armadillos, sloths, anteaters, pangolins (aardvark sometimes
included)
o have very reduced or absent teeth, and many are specialised for feeding on
ants and termites
- “aboreal (tree climbing) specialists”  primates and tree shews (which are not the
same as true shrews!)
Putting it all together
- How are the 18 placental orders related to each other?
- Big puzzle from late 19th to early 20th century
o Now largely solved

Morphological Studies
- Morphological/anatomical studies tended to suggest that the different “types”
represent monophyletic groups or clades e
...
:
o All the “gnawers” = Glires
o All the “insectivores” = “insectivore”
o All the “ungulates” = “Ungulata”
o Bats and flying lemurs = “Volitantia”
- Molectular studies (using DNA and protein sequences) have revised our
understanding
- Some “types” are monophyletic groups/clades – e
...
“gnawers” (rodents and
lagomorphs) form a clade, Glires
- Many other “types” are not monophyletic, they are polypheletic – the result of
convergent evolution
o “insectivore” (“insectivores”)
o “Volitantia” (“flying and gliding mammals”)
o “Ungulata” (“ungulates or hoofed mammals”)
o “Edentata” (edentates)
- Molecular data suggests a relationship between placental phylogeny and
biogeography (where the different orders originated)
- Four superorders of placentals:
o Afortheria  probably originated in Africa
o Xenarthra  probably originated in South America
o Laurasiatheria  probably originated in the northern hemisphere/Laurasia
o Euarchontoglires  probably originated in the northern
hemisphere/Laurasia
Afrotheria
- Includes:
o Some “insectivores”  tenrecs and golden moles
o Some “urangulates”  elephants etc
...
Big toe (hallus) well developed and divergent
2
...
Eye sockets (orbits) large and convergent, small inter-orbital distance,post orbital bar
4
...
Brain case is relatively large
6
...
dental formula is I2 C1 P3 M3 with short premaxilla and snout, upp incisors
arranged more transversely than longitudinally
...
Expected to be tropical, typically arboreal animals
2
...
Gestation long relative to body size; production of small litters and precocial infants
...
9kg)
Omomyids
- Eocene  53-37 Ma
- North America and Europe
- Over 15 species (30g -2
...
35MYA
- Endemic to south and central America
- Primarily arboreal
- Variable life histories
o Callitrichids have multiple offspring
o Cebus and Ateles have slow life histories
- Prehensile tail
- Naked pad with dermatoglyphics (skin writing) or “tail print”
- Used as a fifth limb
- Practice suspensory locomotion
- Only four genera have it; so it DOES NOT characterise all platyrrhines
The Catarrhine Ancestor (downward-facing nostrils)
- Features of both monkeys and apes present
o E
...
bony ear tube; 2 rather than 3 premolars
- But lacked unique characters of each group
o E
...
bilophodont molars
o (OWMs); suspensory shoulders (apes)

(Dozens of) Early Apes
- Ape-like teeth, monkey-like post crania
- Early Miocene 23-16 MYA in Africa
- Forested, moist continent
- Apes lacked suspensory shoulders (plantigrade)
- 17 MYA land connection Africa – Eurasia
- 11-5 MYA apes in Europe and Asia (e
...
Silvapithecus and Gigantopithecus (300kg
ape!))
- Gorilla, chimpanzee, human ancestor???
o Kenyapithecus? Samburupithecus?
Ape Decline
- Mid-Miocene
- Changes in climate; forests shrink
- Monkeys become abundant, apes decline
- Survivors:
o Asia – orangutans, gibbons
o Africa – Chimpanzees, gorillas, humans

WELL I’M A MONKEY’S UNCLE: BECOMING A HUMAN
Classification of Extant Catarrhines (Old World monkeys and apes)

Miocene Hominidae
- Arboreal
- Long fingers and toes
- Brain larger than prior primates
- Large front teeth (incl canines)
- Thick or thin enamel
- No stone tools
Pliocene Hominini
- Terrestrial
- Long fingers and short toes
- Slightly larger brain
- Somewhat reduced canines
- Very thick molar enamel
- No stone tools
What do we get with terrestrial bipedalism?
Recognising a Hominin
- Bipedality
- Mandible shape rounded not U-shaped
- Molars relatively small
- Reduced prognathism
- Diastema/CP3 complex
- Thick tooth enamel
Geographic context
- Earliest = East Africa
- Rift Valley
- Associated Volcanics
- Later in South Africa
Earliest Possible Hominins
- Sahelanthropus tchadensis
- Orrorin tugenensis
- Hominin status hotly debated

-

Assigned to the Tribe Hominini on very limited evidence

Sahelanthropus tchadensis
- Toumai, Chad
- 6-7 Million years ago
- Cranium, teeth
- Extremely large, robust brow ridge
- Hominin status from “smaller canines with apical wear”
Orrorin tugenensis
- 5
...
2 million years ago
- Diagnostic features limited
- Hominin status = differential bone thickness on femoral neck
Diversity in hominin evolution:
2
...
4 million years ago
- Tree covered habitat
- Projecting canines
- Diastema
- Hominin status = apical canine wear, basicranial flexion > other apes
- Suggests non-cjimp like LCA
Australopithecus anamensis
- 3
...
1 million years ago
- Two sites around Lake Turkana, Kenya, also Fejej, Ethiopia
- Dental, cranial and postcranial remains
- More open habitats than Ardipithecus
- Broader molars
- Knee and ankle – Biped
A
...
8-3
...
bahrelghazali
- 3-3
...
afarensis but thinker enamel and different shape, so different
species

-

w/Sahelanthropus, indicates that distribution of early hominins not limited to East
Africa

Kenyanthropus platyops
- ‘Flat-faced Kenyan Man’
- 3
...
5 million years ago
- Cranium: badly crushed vault, face less so, Separate maxilla
- Deep, flat face with strongly built cheek
A
...
4 million years ago
- Taung, Sterkfontein and Makapansgat in South Africa
- Earliest hominin outside East Africa
- Clumps of woodland in open environment
- Postcrania differs little from A
...
6 million years ago
- Found in 1985
- KNM-WT17000
- “the black skull”
- Lake Turkana Kenya
- Brain 400 cm3
- Large cheek teeth and large front teeth
- Dramatic prognathism
- Prominent sagittal crest
P
...
Africa)
- Many sites in Ethiopia, Kenya and Tanzania
- Brain 500+ cm3
- Face flatter (orthognathic) and deeper
- Cheek teeth massive, front teeth small and crowded
- Facial buttressing
- Flaring cheekbones
- 2
...
2 million years ago
South African P
...
crassidens)
- Limited material from kromdraai, more from Swartkrans
- Heavily built face and jaws
- Massive cheek teeth but not as large as A
...
garhi
- 2
...
5 million years ago

Who makes the tools?
- H
...
habilis
o ~1
...
/ A
...
8 million years ago
Homo habilis
- 2-1
...
Africa
- Smaller teeth
- Long arms
- Brain case = 550-700 cc, 50%> than Australopithecus
- Phalanges and tools
Koobi For a: H
...
rudolfensis(?) (26/37)
- Sexual dimorphism?
- KNM-ER 1470: Homo rudolfenisis?
Homo ergaster out of Africa
- On way to SE Asia by 1
...
3-1
...

H
...
8-1
...
erectus
- 1
...
neanderthalensis
- Europe, Middle East
- 150,000 – 30,000 years ago
- Braincase 1200-1750cc
- Postcrainia large, robust
- Evidence for caring burial
Homo floresiensis
- The “hobbit”
- Discovered in 2003
- The island of Flores, Indonesia
- 18,000 years ago
Homo sapiens
- 180,000 years ago – present
- First in Africa
- Braincase 1200-1500 cc
- Skull tall, widest point high
- Small face and brow ridges
- Canine fossa
- Chin
What do we mean by Modern Humans?
Anatomy
- Small face
- Small teeth (canines/molars)
- Big brain
- Long legs/short arms
- Narrow pelvis
Behaviour
- Standardisation of formal stone tools#

-

Shaped bone implements
Fishing and fowling
Burial with goods
Expansion of networks
Use of ‘harsh’ environments
Art/symbolism

PRESERVING BIODIVERSITY
Number of Described species
How many species exist on the planet? A simple question without a simple answer
- We do not even know precisely how many species we have already described:
estimates vary between 1
...
2 million) are arthropods
- About 80% of arthropods (>1 million) are insects, and about 40% of insects
(>400,000) are beetles
o About one in three species on our planet is a beetle
Number of Existing Species
- For an estimation of the total number of species (described and undescribes) on the
planet, it might be best to focus on the most abundant group (i
...
beetles)
- Terry Erwin (1982): Canopy fogging of a single tropical tree (Luechea seemanni) in a
central American rainforest revealed 12,000 beeteles with 163 species being treespecific specialists
o There are globally about 50,000 tropical tree species, which should therefore
harbour 8150000 beetles
o 40% of arthropods are beetles, resulting in a total of 20375000 insects
...
And strikingly, we will probably never know
- Assuming 5 million species exist, and taxonomists describe new species at the same
pace than since Linneaus (1758), we will need another approx
...
The current consensus is to focus on
mitochondrial rather than nuclear genes (example: Cytochrome Oxydase I sequence)

THE EXTINCTION CRISIS
The Extinction Crisis
- Based on conservative calculations, the number of species presently going extinct is
27,000/year, 74/day and 3/hour
Examples for prominent extinctions:
- The passenger pigeon (Ectopistes migratorius) might have once been the most
numerous bird on Earth (about 5 billion individuals lived in Eastern North America,
which may have been comprised 40% of all birds on the continent)
...
The Last individual
(“Martha”) died in a zoo in 1914
- A recent example of an extinct large mammal is the Chinese river dolphin (baiji,
Lipotes vexillifer)
...
org):
- 12% of bird species, 24% of mammal species and 41% of amphibians currently
threatened with extinction
- 20% of freshwater fish have already become extinct worldwide
- Since 1900, 123 freshwater species in North America have gone extinct
Rates of Extinctions – Spatial and Temporal and Scales
- The best datasets are available for birds and mammals
- Terrestrial species on islands, as well as freshwater species have particular
high extinction rates, largely due to vulnerability to habitat perturbation and high
endemism
...

- Introduced species  Brown tree snake introduced to Guam have brought 12 bird
species and 6 lizard species to local extinction
- Overexploitation  Blue fin tuna has become reduced to only 20% in one decade
(80s)
- Disruption of Key species  the local loss of sea otters resulted in a rise in sea
urchins causeing a loss of kelp forests and this major changes in other species
- Pollution, agrochemicals and pharmaceuticals, introduced wildlife diseases…
Habitat Loss and Degradation: The Biggest Threat in all Groups
- Habitat loss and degradation usually has the largest impact, whereas the importance
of other factors varies depending on the taxonomic groups
Biodiversity Hotspots: An Efficient Concept for Conservation?
- Biodiversity hotspots  areas on the global map with particularly high biodiversity
- In 2005, the organisation Conservation International (conservation

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