Monday, December 22, 2008

India Exploration Geologists Fleeing Govt. Petroleum Companies

Geology and livelihoods - 3

I got my bachelor's degree in geology from Fergusson College, Pune. Last week we celebrated the centenary of the department. That is an awfully long tradition of geology in this part of the country. As is inevitable I bumped into colleagues, contemporaries, seniors I had not seen for more than a decade. The department had gone to heroic lengths to get in touch with old students. And I mean really old. There was a sprightly old gentlemen who graduated in 1938 and who soon became one of the star attractions of the afternoon!

I thought it would be fun to compare his lab journal and notes with today's syllabus. What vast differences and maybe some similarities? Come to think of it we still don't teach plate tectonics in second year! :-)

Among the many talks, the one that caught my eye and made me think a bit was a talk by a friend of mine who now works as a senior exploration geologist with a private energy company. He mentioned that around 200 middle and senior exploration geologists have over the last 5 years left government owned oil companies and joined the private energy sector.

Now that is a massive transfer of human capital. I won't say loss of capital since the vast majority of those who left are still working within the Indian oil and gas scenario. Still the government companies feel a little aggrieved. They invested in these people and one fine day all that knowledge base is gone.

I did get the impression talking to friends who have followed this path lately, that financial incentives although certainly important were only part of the motivation. Many, especially those with a Ph.D feel that the government companies don't make full use of their expertise. My friend who is a micro-paleontologist and sedimentologist in a decade and half career with the government didn't always work in his field of specialization.

That is a waste of expertise. Private companies though can't and won't waste. Specialization is rewarded. So while I appreciate the difficulty government companies are facing due to these departures, I see this trend as theoretically a more efficient allocation of human resources.

One practical problem with this theory of efficient resource allocation is that private oil companies hold rights to a very small portion of India's old and new oil producing basins. Private oil companies were only allowed 100% equity in oil and natural gas projects since 2000 under the New Exploration License Policy. So government owned oil companies have ownership of almost all the mature oil fields. Since 2000 nearly 160 new exploration blocks were licensed. Government companies like ONGC along with other national oil companies have done very well in the bidding process winning maybe more than half of those blocks. Not a single international oil major even entered the bidding process.

Besides infrastructure expansion capability, this could turn out to be another limiting factor for India's future oil and natural gas production capacity. India currently imports more than 60% of its oil needs and as its older fields decline, is relying on new finds on the west and east coast offshore basins to boost its domestic oil and natural gas production and relieve it's import requirements. The east coast deep water basins are thought to hold close to 40 trillion cubic feet of natural gas. If true, in terms of energy equivalence this is like doubling India's proved oil reserves as of January 2007 of around 5.6 billion barrels.

The country needs geologic expertise especially in the newer deep water blocks. The government holds rights to a lot of these, but many of their experienced geologists are leaving.

See: Geology and livelihoods

Wednesday, December 17, 2008

Family Encyclopedia Gets Evolution All Wrong

The Dorling Kindersley Family Encyclopedia's chapter on evolution sucks.

I haven't ranted about the treatment of evolution in popular and educational literature for a while so here goes. I was at a friend's place the other day and found his son poring over the tome. I flipped over to the evolution chapter. This is supplementary educational material aimed at middle and high school students and for literate others.

Evolution is as well worked out a theory as any. Instead of impressing upon readers in unambiguous terms that the theory of evolution is a theory of immense explanatory and predictive power and is the only workable theory proposed that explains life, what I found was a disgraceful timidly written apology to creationists.

This is one of the most annoying aspects of many popular writings on evolution. Too much territory is ceded to creationists in an attempt to provide a 'balanced argument" so that people get to know "both sides to the story". Well, there isn't any "both sides to the story" as far as explaining the diversity of life is concerned. Evolution is it. Scientific educational materials need to say that clearly and loudly.

Here are some of the problems I found.

a) Trying to present a balance treatment:

Some scientists argue that by looking at the fossil record we can find out more about the past.

Some people believe that this can lead to a new species and that an animal or plant will adapt to its surrounding so that it has a better chance of survival (another big problem here which I will elaborate on later).

However, some people argue that all life forms on the Earth were created by design, in or close to the form in which they exist today.

So the impression given is that of a field vigorously debated between those who believe in evolution and those who believe in creation. This is totally disingenuous. For one, how does the vast majority of scientists translate into some people believe? In any case the merits of any scientific explanation is not decided on whether some, or many or few people believe in it. It is decided on evidence. All the evidence favors evolution as an explanation for life. This is never made explicitly clear.

b) Adaptations benefit individuals or groups?

Some animals choose their mates by means of sexual selection. A male may have elaborate features such as bright feathers, to attract a mate. Characteristics such as these, which may be beneficial to the species are passed on to the next generation.

There is a distinction to be made here that bears on one of the fundamental questions in evolution. Which entity do adaptations benefit? The individual organism or the species / group? One way to think about this is to consider the genetic relationship of organisms within a group. Organisms within a group vary genetically. The reproduction of individuals is independent i.e. it is not coupled to the reproduction of the group and so genes can increase their own reproduction independently of other genes in the group.

Natural selection will favor such genes that allow its bearer to reproduce more than other organisms in the group. Since differential survival and reproduction of individuals is a much faster process than the differential origin and extinction of groups, such genes will spread through the population even if they might be harmful to the group as a whole.

For example it might have been beneficial to the group if peacocks waste less energy developing an elaborate plumage and concentrate on gathering food and reproducing. An elaborate plumage also may expose the population to predators. Keeping plumage inconspicuous would have been a good group adaptation. Except that individual female choice for brightly colored plumage drives the evolution of bigger and brighter plumage, even though there may be a conflict between what is good for the individual and what is good for the group.

I can think of a simpler example to teach middle and high school students. In large penguin colonies or for that matter any large bird colony, Mama after grabbing food goes through an elaborate search among the thousands of squawking babies to find her own baby to feed. If individuals really strive for the benefit of the group, a more efficient group adaptation would have been for Mama to feed any child which is nearest to her. That way offspring are assured of getting food from some adult.

Such a hypothetical altruistic colony may do better than a colony full of selfish individuals. For example perhaps it is less likely to go extinct when scarcity strikes. But such a altruistic colony is unlikely to evolve in the first place since it is susceptible to invasion from a selfish mutant. A mutant parent with the ability to find and feed her own child will be able to produce more children than other altruistic parents, since she will also benefit from strangers feeding her children. The mutation will spread through the population (through her children) and destroy the altruistic group adaptation.

So natural selection will evolve adaptations that benefit the individual and not the species.

In only exceptionally rare cases such as eusocial insects, where only one individual in the group reproduces, and all other individuals are offspring of that founder will we see adaptations that benefit the group. In this case all the non-reproducing individuals share genes with the founder and the only way to pass on a proportion of one's genes is to selflessly help the founder reproduce more and maintain the group.

c) Inheritance of acquired characters.

The process of adaptation occurs when an organism evolves in a certain way to make it better suited to the environment. Some people believe that this can lead to a new species and that an animal or plant will adapt to its surrounding so that it has a better chance of survival

An organism may undergo change due to a number of processes, such as natural selection and adaptation, induced by the environment in which it lives.

No, No, No.

I am convinced that this is still the most popular perception of how evolution works. A lot of people I have talked to about evolution (not all of them with a science background) are familiar with the terms natural selection and adaptation but they understand it to mean the inheritance of acquired characters.

But individual organisms don't adapt that it has a better chance of survival. Evolution is not a teleologically process. And individual organisms during their lifetime don't adapt or change to changing conditions and then pass on those changes to their offspring. This inheritance of acquired characters doesn't work because of the separation of the somatic cells that make up the bulk of the body and the reproductive cells that are passed on to build the next generation.

Changes induced if any by the environment in the somatic cell lines don't get incorporated in the genetic material of reproductive cells.

Evolution is a process that takes place in populations. When the environment changes, those individuals who happen to possess traits that help them reproduce more than other individuals will produce more children. Those traits will then become more common in the population. Screening of these traits through successive filters of natural selection over generation results in a better and better fit between successive generations of descendants and the environment.

But it is critical to remember that these changes don't happen during the lifetime of an individual organism. Evolution takes place over generations. Organisms at any one time have different traits from those their ancestors possessed.

Evolution is not taught well if at all at the high school level in India. Biology teachers are not well versed in evolution, they being a product of a system without a comprehensive evolution syllabus at even the undergraduate college level. If an enterprising teacher does introduce the subject it will be by reading up of supplementary materials like this encyclopedia. That won't help students understand evolution any better. And for most students who give up the sciences after school this will be just about their only reading of evolution.

That may hurt us in the long run. Scientific American has an article on why knowledge of evolution can be useful to non-specialists too. Improved public understanding of the subject will have a significant influence on policy decisions on health care, ecology, agriculture.

What has been your experience with such large encyclopedia publications? Is the geology section for example worth referring to? Do you think it is written by experts in the field and can be relied upon?

Monday, December 15, 2008

100 Things I Have Done As a Geologist

Geotripper has started this meme. List out 100 things you have done as a geologist. The entire list is below with stuff I have done or experienced in bold. My explanations in italic.

1. See an erupting volcano
2. See a glacier - Glacier National Park, Montana
3. See an active geyser such as those in Yellowstone, New Zealand or the type locality of Iceland
4. Visit the Cretaceous/Tertiary (KT) Boundary. Possible locations include Gubbio, Italy, Stevns Klint, Denmark, the Red Deer River Valley near Drumheller, Alberta.
5. Observe (from a safe distance) a river whose discharge is above bankful stage
6. Explore a limestone cave. Try Carlsbad Caverns in New Mexico, Lehman Caves in Great Basin National Park, or the caves of Kentucky or TAG (Tennessee, Alabama, and Georgia)- Lurray Caverns in Virginia.
7. Tour an open pit mine, such as those in Butte, Montana, Bingham Canyon, Utah, Summitville, Colorado, Globe or Morenci, Arizona, or Chuquicamata, Chile. - Mid Proterozoic porphyry copper deposit, Malanjkhand, central India
8. Explore a subsurface mine. - Late Paleozoic coal deposits in central India Gondwana rift basins.
9. See an ophiolite, such as the ophiolite complex in Oman or the Troodos complex on the Island Cyprus (if on a budget, try the Coast Ranges or Klamath Mountains of California). - Cenozoic ophiolite in Ladakh Himalayas
10. An anorthosite complex, such as those in Labrador, the Adirondacks, and Niger (there's some anorthosite in southern California too).

11. A slot canyon. Many of these amazing canyons are less than 3 feet wide and over 100 feet deep. They reside on the Colorado Plateau. Among the best are Antelope Canyon, Brimstone Canyon, Spooky Gulch and the Round Valley Draw.
12. Varves, whether you see the type section in Sweden or examples elsewhere.
13. An exfoliation dome, such as those in the Sierra Nevada.
14. A layered igneous intrusion, such as the Stillwater complex in Montana or the Skaergaard Complex in Eastern Greenland.
15. Coastlines along the leading and trailing edge of a tectonic plate (check out The Dynamic Earth - The Story of Plate Tectonics - an excellent website).
16. A gingko tree, which is the lone survivor of an ancient group of softwoods that covered much of the Northern Hemisphere in the Mesozoic.
17. Living and fossilized stromatolites (Glacier National Park is a great place to see fossil stromatolites, while Shark Bay in Australia is the place to see living ones) - Proterozoic central and south India.
18. A field of glacial erratics
19. A caldera
20. A sand dune more than 200 feet high

21. A fjord - New Zealand
22. A recently formed fault scarp
23. A megabreccia - Himalayas
24. An actively accreting river delta- Krishna river delta east coast India
25. A natural bridge - Deccan Basalts about 100 km east of Pune, India
26. A large sinkhole - Virginia, Florida
27. A glacial outwash plain
28. A sea stack
29. A house-sized glacial erratic
30. An underground lake or river - Florida
31. The continental divide - Glacier National Park, Montana
32. Fluorescent and phosphorescent minerals
33. Petrified trees - Cretaceous, Central India
34. Lava tubes - Deccan Basalts, West India
35. The Grand Canyon. All the way down. And back.
36. Meteor Crater, Arizona, also known as the Barringer Crater, to see an impact crater on a scale that is comprehensible
37. The Great Barrier Reef, northeastern Australia, to see the largest coral reef in the world.
38. The Bay of Fundy, New Brunswick and Nova Scotia, Canada, to see the highest tides in the world (up to 16m)
39. The Waterpocket Fold, Utah, to see well exposed folds on a massive scale.
40. The Banded Iron Formation, Michigan, to better appreciate the air you breathe.

41. The Snows of Kilimanjaro, Tanzania,
42. Lake Baikal, Siberia, to see the deepest lake in the world (1,620 m) with 20 percent of the Earth's fresh water.
43. Ayers Rock (known now by the Aboriginal name of Uluru), Australia. This inselberg of nearly vertical Precambrian strata is about 2.5 kilometers long and more than 350 meters high
44. Devil's Tower, northeastern Wyoming, to see a classic example of columnar jointing - Not in Wyoming, but seen classic columnar jointing at Gilbert's Hill, Mumbai (Bombay).
45. The Alps.
46. Telescope Peak, in Death Valley National Park. From this spectacular summit you can look down onto the floor of Death Valley - 11,330 feet below.
47. The Li River, China, to see the fantastic tower karst that appears in much Chinese art
48. The Dalmation Coast of Croatia, to see the original Karst.
49. The Gorge of Bhagirathi, one of the sacred headwaters of the Ganges, in the Indian Himalayas, where the river flows from an ice tunnel beneath the Gangatori Glacier into a deep gorge.
50. The Goosenecks of the San Juan River, Utah, an impressive series of entrenched meanders.
51. Shiprock, New Mexico, to see a large volcanic neck

52. Land's End, Cornwall, Great Britain, for fractured granites that have feldspar crystals bigger than your fist.
53. Tierra del Fuego, Chile and Argentina, to see the Straights of Magellan and the southernmost tip of South America.
54. Mount St. Helens, Washington, to see the results of recent explosive volcanism.
55. The Giant's Causeway and the Antrim Plateau, Northern Ireland, to see polygonally fractured basaltic flows.
56. The Great Rift Valley in Africa.
57. The Matterhorn, along the Swiss/Italian border, to see the classic "horn".
58. The Carolina Bays, along the Carolinian and Georgian coastal plain
59. The Mima Mounds near Olympia, Washington
60. Siccar Point, Berwickshire, Scotland, where James Hutton (the "father" of modern geology) observed the classic unconformity

61. The moving rocks of Racetrack Playa in Death Valley
62. Yosemite Valley
63. Landscape Arch (or Delicate Arch) in Utah
64. The Burgess Shale in British Columbia
65. The Channeled Scablands of central Washington
66. Bryce Canyon
67. Grand Prismatic Spring at Yellowstone
68. Monument Valley
69. The San Andreas fault
70. The dinosaur footprints in La Rioja, Spain

71. The volcanic landscapes of the Canary Islands
72. The Pyrennees Mountains
73. The Lime Caves at Karamea on the West Coast of New Zealand
74. Denali (an orogeny in progress) - Himalayas
75. A catastrophic mass wasting event
76. The giant crossbeds visible at Zion National Park
77. The black sand beaches in Hawaii (or the green sand-olivine beaches)
78. Barton Springs in Texas
79. Hells Canyon in Idaho
80. The Black Canyon of the Gunnison in Colorado

81. The Tunguska Impact site in Siberia
82. Feel an earthquake with a magnitude greater than 5.0.- Recent September earthquake near Satara, Maharashtra was just about 5.0
83. Find dinosaur footprints in situ
84. Find a trilobite (or a dinosaur bone or any other fossil) - Cretaceous south India, Ordovician S. Appalachians.
85. Find gold, however small the flake
86. Find a meteorite fragment
87. Experience a volcanic ashfall
88. Experience a sandstorm
89. See a tsunami
90. Witness a total solar eclipse

91. Witness a tornado firsthand. (Important rules of this game).
92. Witness a meteor storm, a term used to describe a particularly intense (1000+ per minute) meteor shower
93. View Saturn and its moons through a respectable telescope.
94. See the Aurora borealis, otherwise known as the northern lights.
95. View a great naked-eye comet, an opportunity which occurs only a few times per century - Halley's comet 1986
96. See a lunar eclipse
97. View a distant galaxy through a large telescope
98. Experience a hurricane
99. See noctilucent clouds
100. See the green flash

Looks like I have a lot of ground to cover. Especially, what.... you geologist?, Canyon?!!!!

Wednesday, December 10, 2008

Litigation to Ban Blur Google Earth Filed in India

From DNA a report that Mr. Amit Karkhanis who is an advocate has filed a Public Interest Litigation (PIL) with the Bombay High Court requesting the Court to direct Google to blur images of sensitive areas in the country.

“This website aids terrorists in plotting attacks,” the plea states.

Now take a look at the targets the terrorists hit in Mumbai. A train station, a pub, a hospital and a hotel. These are the kinds of locations along with a street map that even shoddy government of India approved tourist literature actually highlight! Blurring locations deemed worthy of secrecy ain't going to stop terrorists from randomly picking any crowded area in India's teeming cities and causing mayhem.

City street maps and points of interest are available independent of Google Earth images. Most smart phones these days come preloaded with street maps and location based navigation services. It is an exercise in silliness to blur a few location here and there and hope that will deter terrorists.

Maybe it makes sense to blur locations of military and strategic interest. I really don't believe so, since spy agencies of various countries have already mapped those. And if the spy agency is in collusion with the terrorists then you have a bigger problem at hand that won't be solved by banning Google Earth.

I hope the Bombay High Court shows Mr. Karkhanis the correct place to file such PIL's.

Which is in the garbage can.

Sunday, December 7, 2008

Some Great Lines from Edward O. Wilson

From NPR's Science Friday a talk on ant societies and superorganisms by Edward O. Wilson and Bert Hölldobler.

E.O Wilson on the dominant role of females in ant societies:

I am a feminist too, but ant societies are liberalism run amok

On the success of the socialist model in ants:

Marx was right about socialism. He just applied it to the wrong species


Bert Hölldobler on within group and outgroup recognition:

Maybe we need to maintain some level of xenophobia otherwise we won't enjoy a football match.

What a fascinating talk! Do Listen.

Thursday, December 4, 2008

Groundwater Flow in Basalts, Caught on Video

The volcanic rock basalt underlies the city of Pune and much of the state of Maharashtra. Its rock mass is made up of an interlocking fabric of crystals and it doesn't have interconnected pore spaces through which water could be transmitted. The permeability of the rock mass is negligible. But basalts can be prolific aquifers. The reason is the various kinds of fractures and joints that serve to store and transmit water.

I came across a construction site near my house the other day and saw that they had dug a pretty deep hole for a foundation. I could see a thick rock profile consisting of two basalt flows. The upper flow was an amygdaloidal vesicular basalt. The lower one was a compact basalt. These are field terms used to categorize flow units with different physical characteristics. At the junction of the two flows was a fractured zone. The fractures were horizontal giving the basalt a sheeted appearance. And water was flowing out of these fractures at a fair pace. Take a look.

Groundwater flow in Basalt

This narrow flow zone which is a few feet thick is really the aquifer in this case. The compact basalt below forms the base of the system. Above this water seep you can see that the amygdaloidal basalt is bone dry. I wrote before about the enormous influence basalt hydrology has on the lives of Maharashtra farmers. You can get an idea why that is so. Finding water in basalts can be tough work because of such narrow permeability zones. Farmers often have the misfortune of farming tiny plots of land over basalts with no or very deep permeability zones. Digging wells into basalts is expensive and risky. Without proper geological guidance many poor farmers remain without access to groundwater.

So far this shallow groundwater system is not being exploited as a resource within the city of Pune. But that might change. Looking twenty years ahead, an expanding population and more water intensive life styles as people become prosperous might strain the surface water supply, which currently is sufficient to give citizens of Pune one of urban India's highest per day per capita allowance of around 200 liters.

Add to that are the vagaries of the monsoons. Even without global warming induced perturbations to rainfall, Indian monsoons are characterized by a decadal scale natural variability. Pune over the last 3-4 years has experienced higher than average rains but extended periods of lower than average rainfall is also a likely scenario in the future. A combination of lower rainfall and higher population might mean that the surface water reservoirs fall short of supplying enough water. The aquifer underneath Pune might gain importance in this context.

Unfortunately hydrologists don't really know how much water is present in the aquifers underneath Pune. The state ground water board periodically issues completely useless statements about the level of groundwater either going up or going down by said amounts. These are based on a few observation wells in areas where the aquifer is not being exploited. But there is practically no quantitative assessment of what will happen to the groundwater system if people suddenly start sucking water out of it. The system has not been studied under stress.

There is an opportunity to do that. On the outskirts of the city private water suppliers have sunk dug wells and bore wells. Year after year they are pumping water out of the shallow and deep aquifers. The water balance is not understood. How much should be taken out so that natural recharge will balance extraction? But I don't see government scientists rushing with their measuring tools to take advantage of these potential data points. Scientific progress relies as much on opportunism as on any other attribute. But state hydrologists lack the flexibility to deviate from their 2 year or 3 year of 5 year plans and schemes they are directed to follow.

Pune must have a science backed plan if and when the time comes to start exploiting the underlying aquifers. The time to start a serious research program is now.

Monday, December 1, 2008

Why An Undergraduate Thesis Is So Useful

My Bookshelf Series - 4

My bookshelf series continues. This one is from one of my favorite books on evolutionary biology, John Tyler Bonner's Life Cycles.

Some years ago a friend who happened to be a distinguished mathematician came to Princeton and we arranged to have lunch. He came to my office a bit early, so I asked him to please have a seat and find some reading matter on the shelves and I would return shortly. When I came back, to my horror he was reading my undergraduate senior thesis, the first half of which is an analysis of the problem of development using symbolic logic. I admonished him for picking it out in a room filled with good books. He replied, " Don't be silly, this is wonderful". When I asked him how he could say something so absurd, he said, " You don't understand. What's wonderful is that you got this out of your system so early in life".

Quite correct. I never wrote a senior undergraduate thesis, but my Master's dissertation? I keep that locked up. But why go back so far? I cringe with embarrassment at some early posts in this blog.

See: My Book Shelf Series

Giant Protist Tracks and Early Animal Evolution

Chris at Highly Allochthonous has an interesting post on recently discovered tracks made on a sandy sea floor by a giant protist. Similar fossil tracks have been found in early mid Proterozoic sediments. Chris gives an example from Australia (2 billion years old) but there are reports of tracks and even interpreted burrows from mid Proterozoic Vindhyan basin (1.5 -1.8 billion years old) of central India. These have been interpreted by some researchers to point to a deeper origin of metazoans (multicellular animals) than molecular phylogeny and the bulk of the body fossil record support. These data suggest a timeline of around 600-700 million years ago for the origin of metazoans.

The tracks made by the unicellular protist means that such deep origin interpretations are again in doubt. I've been reading claims and counterclaims on this issue for quite a while. I would like to add to what Chris has discussed by giving a list of the reasons why most paleobiologists feel that the pattern of appearance of macroscopic animal fossils faithfully records evolution. In effect the list below is a critique of the view that animals evolved much much before what the macroscopic fossil record indicates. I have taken these from an essay by Simon Conway Morris, an expert in early animal evolution.

1) these ancient “traces” are typically highly restricted in distribution and sometimes only known from a single slab of rock.

2) no explanation is offered as to the failure of the “organisms” to diversify in what would otherwise appear to be an ecological “vacuum”.

3) the structures in question are almost all remarkably different from one another.

4) all other evidence points to a “microbial world” uneffected by a putative macroscopic ecology ( i guess by this he means that the preservation of bacterial mats as stromatolites suggest a minimal disturbance of the sea floor by large critters).

5) the important fact that even in late Neoproterozoic sediments yielding exquisitely preserved softbodied algae, there is no corresponding preservation of metazoans.

So there are very good reasons to be skeptical of claims that diverge widely from evidence given by molecular phylogeny and the body fossil record.

There is a misconception I have encountered that for several billion years "nothing much" of evolutionary importance took place, that the planet was inhabited by boring bacteria and then unicellular eukaryotes. Then suddenly in the early Cambrian macroscopic life took hold. Such a view prevails because people focus on the evolution of form. But we do know that we share with protists many of the molecular mechanisms responsible for cell physiology and even more complicated processes like gene shuffling and meiosis are present at various levels of development in protists. All these must have been evolving for hundreds of millions of years before the origin of metazoans.

Multicellular animals evolved from protist ancestors. They were built on this already existing molecular scaffolding.

The origin of metazoans can be seen in this light as evolution favoring an increase in size made possible by ecological triggers perhaps like an increase in the level of atmospheric oxygen by the latest Proterozoic. The novelty was the evolution of development. Creatures grew larger by cells dividing into specialized groups and sticking to each other for a large part of the life cycle of the organism.

Even this did not appear in a jiffy. The Cambrian "explosion" is an awful and nebulous term that confuses more than clarifies. We now have enough of a fossil record spanning the latest Proterozoic -Mid Cambrian - spanning nearly 60 million years- that indicates the evolution of successive grades of animal complexity in several bursts of diversification. The early-mid Cambrian phase (the "explosion") represented by Chenjiang- Burgess type fauna was the youngest of such events in which triploblastic animals rapidly (geologically speaking) diversified. The figure below summarizes our present state of knowledge.

Source: Origin of Phyla

Complex multicellular animals evolved from slightly less complex ancestors which in turn....