The document discusses the Ediacaran period and the unique organisms that existed during this time in the Precambrian era before the Cambrian explosion. Many of these organisms had unusual forms and structures unlike anything seen before or since, making them very difficult to classify. Some possibilities for their disappearance include changes in oxygen levels, sea level, increased competition from Cambrian organisms, or disruption of microbial mats which provided food and oxygen. The Ediacaran period proved to be an important turning point in the history of life that forced scientists to revise views on the origin and evolution of animals.

1. Trials & Tribulations Chapter 4 1
Mysterious Ediacaran
Dickinsonia Charnia
Verisimilus– Wc – cc Verisimilus – Wc – cc
Trace fossil Kimberella
Verisimilus - Wc – cc A.Nagovitsyn-Martin-Wc - cc

2. Trial Tribulations 2
Spriggina
fossil Liferestoration
Merikanto – Wc – cc M.D.Stefano – Wc – cc
Spindle shaped Fractofusus Cyclomedusa - attachment disc
Misra.-Mistaken point – Wc – cc Verisimilus – Wc – cc

3. Trials & Tribulations 3
Cloudina
G.Bartlett-Smith-Wc –cc
Fractofusus Misrai
Artists impression of community Clustered grouping
C.G.Kenchington A .G.Liu
cam.ac.uk – research - cc .

4. Trials &Tribulations 4
Ediacaran garden
Ryan Somma – Snmn –cc – Aun biology-Wordpress.com
A lovelyunder see garden
a partingpresentfrom Cryogenian!
an enigmatic Ediacaran
is the last periodof Precambrian
Announcing birthof animals
across the seven seas
it displayed them as if they were
flower pots in a great garden

5. Trials & Tribulations 5
for these unique organisms
were mostlysessile soft delicate,
and beautifullikeflowers;
( althoughsomewere slightlymobile )
Sea beds were carpetedthese days
with green microbialmats
mostlyof Cyanobacteriaand Algae
providing bed & food to newcomers
which were of a varietyof unusual
forms designs and lifestyle
and apparentlybelongedto many
distinct distinguishable groups
Some of these animals
looked likeplant leaves
infactCharnia becamefamous
due to its frond likefeatures

6. Trials & Tribulations 6
Someothers looked like
Inflatable soft velvety Quilts
with beautiful patterns as
in well known Dickinsonia
Still othersappeared in calcareous
funnelswithinfunnelsform
such as Cloudina livingin such
extraordinaryshelled tubes
There were many more strangeforms
like spindleshapedFractofusus
with ferns like fronds ,clusterd grouping, and
propagationby ‘stolons’ as in plants
or by releasingpropagules in water;
the wonder ,however, does not
cease here for it can switch between
these modes strategically !

7. Trials & Tribulations 7
These and Cloudinalikethereare
other organisms whose forms
and lifestrategies defy description for
they have no paralleltill thistime
It is thereforedifficult to determine
theiraffinityor classifythem
in any of the known categories
giving riseto interestingdebates
Were Dickinsonia and Spriggina
Annelida or Arthropoda?
Kimberella a Mollusc?Cloudinaa Coral ?
Charniaa Seapen ? and so on
There is , however, one point
on which most agreethat they were
complex, multicellular,macro organisms
showingseveral animal features

8. Trials & Tribulations 8
Someshowingsigns of burrowing
or worm likeor slug like muscular motion
someothers showing grazing or predation !
and asexual or sexual reproduction
But the fact is thesenovel organisms
are very enigmaticand likes
of many of them were not seen
beforeor after Ediacarantimes
And the questionthat it has
raised naturally is – Why ?How!
What, if any ,relation is
between them and Cambrianbiota?
For their sudden disappearance somesay
changes in atmosphericO2 or sea level
were responsible ;othersdon’t rule out
competitionof survivorswith Cambrian

9. Trials & Tribulations 9
The latest theoryis that the
Seabed microbial mats were
responsiblefor their appearance,
life, as well as disappearance
for they providedrequiredO2 & food
for living, but animals increasein size
and motion decreased microbesand
disturbedsediments causingtheir death
Their relationshipwith
one or the other moderntaxa
is , however , stillnot clear
and continuesto be debatable.
All saidand doneEdiacaranhas
proved a turningpoint in History
which forced us to reviseour views
about originand evolution of animals.

10. Trials & Tribulations 10
Pennatula
Dann Blackwood– usgs – Wc – Publicdomain
Was Charnia ancestorof this modernpen
A beautifullivingdescendant?