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  • Coenozoic : Mammals developed further, including primates. Development of birds and flowering plants is evident. Global cooling occurs (i.e. the most recent ice ages, which caused a drop in sea levels. This allowed development of land bridges between NorthAmerica and Asia, also between India and Sri Lanka and between Australia and the islands to its north. These land bridges assisted greatly in the migrationof species to new land masses).

Hominid evolution started during the Coenozoic. This will be discussed more fully in Grade 12.

Two types of flowering plants (Angiospermae)

Models of Australopithecus , an early hominid
Baby mammoth

Critical evaluation

The geological column summarises a commonly accepted evolutionary theory about life’s history. As with most scientific theories, not all scientistsagree about the theory. Criticisms include the following:

  • The sequence (order) of fossils given in the geological column is not found anywhere on earth. Instead, there are many places where ‘older’ layers are found on top of ‘younger’ layers.
  • There are many gaps in every sequence. To explain this, palaeontologists suggest that about 2/3 of all the kinds of organisms that ever lived could not have left any fossils.(Palaeontologists are scientists who study fossils and try to use then to reconstruct the past.) It is reasonable to expect that many soft-bodiedcreatures would not have been fossilised. However, it is strange that there are gaps in the fossil records even for creatures with hard shells and strongbones.
  • The dating methods used to date rocks might not give valid dates. This is discussed in the section about fossils and dating.

It’s been believed for many years that modern birds developed from reptilian ancestors, as dinosaur fossils often showed AVIAN or ‘bird-like’ features. There was thus much excitement when the first fossil of a “missing link” between birds and dinosaurs wasfound, the so-called Archaeopteryx. Around 10 such fossils have been found to date. Read the information below:

Left is a specimen of Archaeopteryx , and right is an artist’s impression of the skeleton in an upright position. Note the very fine feather impressions, including the flight feathersof the wings. Despite its obvious avian nature, Archaeopteryx has a hand virtually identical to other dinosaurs such as Velociraptor .

Artist's impression of the animal

A mounted archeopteryx model. Note the teeth.

Use the pictures below and on the previous page to compare the skeletons of a dinosaur, Archaeopteryx and a modern bird. In your answer, give differences and similarities between Archaeopteryx and dinosaurs, and between Archaeopteryx and birds.


Archaeopteryx vs Dinosaur:

1 Jaws have teeth
2 Hand / arm has claws
3 Long bony tail present
4 Presence of gastralia or dermal ribs (not attached to spine)

Archaeopteryx vs Dinosaur:

1 Long forelimbs, like wings Short forelimbs
2 Feathers present No feathers
3 Hand has three claws Hand has five claws
4 Furcula / wish bone present No furcula present

Archaeopteryx vs Modern bird

1 Feathers are present
2 Forelimbs are long and wing-like
3 Furcula / wish bone present (fused clavicles)
4 Bones of the lower forelimb are separate

Archaeopteryx vs Modern bird

1 Teeth in jaws No teeth in the beak
2 Claws on forelimbs Forelimbs without claws
3 Long bony tail Short tail bones / pygostral present
4 No breast bone Breast bone with a keel

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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why and for what was five kingdom of classification of organisms introduced
give the ans as fast as possible
Comment on the ozone depletion over the period of 1982 to 1996
Mpho Reply

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Source:  OpenStax, Siyavula: life sciences grade 10. OpenStax CNX. Apr 11, 2012 Download for free at http://cnx.org/content/col11410/1.3
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