DINOSAURS PLUS
‘The very first requirement for ecological stability
is a balance between the rates of birth and death . . .’
Gregory Bateson
The next significant part of our story begins in what paleontologists call the Triassic period, around 240 million years ago, when reptile families were diversifying after the Third Major Mass Extinction. Among them were the ancestors of dinosaurs, which, although not direct ancestors of humans, would introduce ways of being that contributed hugely to subsequent evolution.
Among the reptiles were also the ancestors of mammals, which were cold-blooded like reptiles, but had earbones and jaws that moved back and forth.
One was the pig-sized plant-eating lystrosaurus. (Around this time what seems to have been a lystrosaurus left tracks above a layer of coal, recently rediscovered in today’s Bellambi Colliery near Sydney.) There were also stubby-legged carnivorous mammal ancestors that scientists call cynodonts.
Plants were also diversifying, as Pangaea started to break up into two smaller supercontinents. In the north was Laurasia: today’s Eurasia with North America attached to its west coast. In the south was Gondwana: today’s India, Africa, South America, Australia and Antarctica all joined.
A minor mass extinction was followed 35 million years later by the Fourth Major Mass Extinction, and renewal probably took 100 million years.
But then, as the supercontinents kept fragmenting, animal diversity would return and increase as they filled the niches caused by isolation. The scientific term for this is convergent evolution. A later example is six kinds of carnivore with sabre-teeth, all emerging independently in similar but dispersed ecosystems.
As part of this process several dinosaur species were now evolving and multiplying on different continents. They seem to have been descendants of reptiles and forerunners of birds - scaly at first, but with a few eventually being able to regulate their body temperature, and in the process developing feathers.
Like reptiles and amphibians, they had proportionally small, simple brains and acted mostly by instinct, but their legs were strong enough for them to stand upright and this gave them a distinct advantage.
The first ones were what scientists call lizard-hipped dinosaurs, mostly carnivores running on very strong back legs and using short forelegs to grasp a reptile or amphibian as they killed it with a bite. But soon there were some browsing dinosaurs moving on four legs.
A few of them apparently lived and travelled in groups, but they seem to have been no more than acquaintances, clumping together to present a solid front as protection from the carnivores. They spent most of their time consuming the plants that were all around them.
By now in the forests more primitive trees had given way to cycads, gingkos and early cone-bearing trees (conifers), with tough branches and leaves. Nevertheless the browsing dinosaurs were able to eat and digest them - another example of coevolution.
The new trees put their male and female organs in the centre of a cone, and their male cells in grains of pollen. When the cones opened, some of a male cone’s pollen drifted onto the organ in a nearby female cone. Then the female cone closed up to protect the fertilized seeds as they developed, and later re-opened to release them onto the ground.
Any nearby dinosaur excreta provided a rich fertilizer to aid germination, and there were also enough seeds for some to be consumed by various passing animals.
Some dinosaur families were taking an even more significant evolutionary step. Their females laid fewer eggs than reptiles, and both parents protected, warmed and turned them, and then fed and protected the hatchlings.
Since this behaviour called for a very important new way of knowing and interacting, the hormonal activity that signalled pleasure and pain through their nervous system must have expanded.
A very significant new way of living as an animal had emerged: support of one’s young.
Supporting hatchlings required other kinds of brain expansion in adult dinosaurs. They had to keep them supplied with food, and they also had to keep track of a number of older, mobile, offspring.
So they must have developed an awareness of quantity and number – admittedly very basic by later standards. A rough verbal translation of their processing of quantity might be: ‘Have I got enough for them this time (or do I have to go out again)?’ And of their processing of number: ‘I think there should be more than one of them here.’
Meanwhile a few dinosaurs were leaping across the ground, gliding from tree to tree, and perhaps even flying short distances.
Among them were ancestral birds, with teeth, long bony tails, clawed digits, and primitive wings that may have been used for cooling or gliding rather than flight.
In the early conifer forests as well were the first tiny mammals, most only a few centimeters long and making a living as far out of the way of adult dinosaurs as they could.
Like all other existing land-animals but unlike later mammals, the females still had a cloaca (single cavity) - hence the name of their living descendants: monotremes, literally ‘one hole’. And like all other land-animals apart from some dinosaur species, the adults led a solitary life, with the male joining a female only to mate, and often having to fight off or wear out any other males first.
(Today monotremes are extinct everywhere but in Australia and New Guinea. They include the echidna and the platypus, a cat-sized distant relative of which would appear later in a Gondwanan rainforest – on today’s Lightning Ridge.)
Monotremes differed from reptiles in quite a few ways.
Firstly they were warm-blooded and furred and so they could spend the day asleep in a burrow, coming out to feed and mate at night when most dinosaurs were asleep. Secondly they had efficient smell-sensors that helped them find their way to high protein food as quickly as possible. They ate mostly seeds, insects, eggs and small reptiles, and with a fast metabolism they needed food several times a night.
But the most significant difference was that a mother nurtured her young, and she did it in a surprising new way.
She laid a few fertilized eggs in a burrow, but when her tiny hatchlings emerged they were naked and very immature. She kept them warm, fed them with milk oozing through pores in her soft belly-skin, and protected them from any animals that would regard them as food – until they developed the form and agility they would need to survive on their own.
This nurturing was part of a reproductive cycle coordinated by the hypothalamus, a master-gland evolving as part of a new layer around the pre-programmed brain she inherited from reptiles. (Scientists call this new layer a cortex.)
A monotreme female’s hormones ensured that she came into heat (or oestrus), sent out a ‘Come and get it’ scent, and then tested the fitness of responding males by leading them on a not-so-merry chase. Other hormones later prompted her to protect, nurture and suckle her young.
When a male reached maturity his hypothalamus had a less complex task, co-ordinating hormones that prompted him to respond to a female scent and to compete with other males.
These internal calls for action, most of them particular to a monotreme’s gender, are the basis of our emotions. Since they would develop further with true mammals, it seems clear that a new way of living was emerging: action in response to gendered emotions.
Monotremes were pioneering the sexual specialization that mammals are known for among vertebrate animals, and as part of this process the amygdala began to develop slightly differently in males and females.
Meanwhile some hardy insects like cockroaches were thriving among the plants and other animals. Their descendants would have to adapt very little in order to survive until today (for instance drier conditions led to burrowing and then modified wings).
And they are expected to survive well into the future, no matter what it brings. One of their superior survival strategies is that some of their females keep their eggs inside their bodies until they are ready to hatch, and a few even give birth to fully formed offspring.
Near the ocean-floor were the ancestors of today’s squid, spiral-shelled mollusks whose adult size ranged from a centimetre to two metres in diameter.
During their lives they made strong closely coiled shells, attaching identically proportioned but progressively larger chambers as they grew inside them. They controlled their buoyancy and movement by varying the amount of air and water in the chambers.
Although they were not long-term survivors like cockroaches, their influence would last long after they became extinct. Today they are an iconic example of the various organic patterns that have inspired human ideas of symmetry and rhythm over thousands of years.
(Throughout what is Australia today ammonite fossils of all sizes are commonly found in limestone rocks, formed from the remains of creatures with softer shells.)
Back in our story the supercontinent Gondwana was now beginning to break up. The west coast of Africa was splitting off from the east coast of South America, forming what we call the southern Atlantic Ocean. And India was separate from the western coast of Australia and moving north, creating the Indian Ocean as it went.
A split was opening in Laurasia too, forming the northern Atlantic Ocean between Eurasia and North America.
And the Panthalassa Ocean was contracting into the Pacific Ocean. Of course all these oceans are still really sections of one vast ocean.
(In the areas that would be Australia’s coastline there were great volcanoes along today’s east. And in today’s west, huge lava flows poured up from 100 km below the sea, covering an area of land 200 km wide and 70 metres deep. Several comets and asteroids also hit Australia around this time. One left a 24 kilometre crater at Gosses Bluff, in the Northern Territory. Today it is one of the best-preserved ancient impact sites on Earth.)
In a wonderful greenhouse climate from north to south across Earth, plants with seeds were multiplying and diversifying. Now they included more modern pine-trees, which were creating huge forests everywhere, helped by underground networks of microbes, newly evolved fungi, and earthworms – and also by many insects. And trees, microbes, fungi, earthworms and insects were all thriving.
Among the reptiles were also the ancestors of mammals, which were cold-blooded like reptiles, but had earbones and jaws that moved back and forth.
One was the pig-sized plant-eating lystrosaurus. (Around this time what seems to have been a lystrosaurus left tracks above a layer of coal, recently rediscovered in today’s Bellambi Colliery near Sydney.) There were also stubby-legged carnivorous mammal ancestors that scientists call cynodonts.
Plants were also diversifying, as Pangaea started to break up into two smaller supercontinents. In the north was Laurasia: today’s Eurasia with North America attached to its west coast. In the south was Gondwana: today’s India, Africa, South America, Australia and Antarctica all joined.
A minor mass extinction was followed 35 million years later by the Fourth Major Mass Extinction, and renewal probably took 100 million years.
But then, as the supercontinents kept fragmenting, animal diversity would return and increase as they filled the niches caused by isolation. The scientific term for this is convergent evolution. A later example is six kinds of carnivore with sabre-teeth, all emerging independently in similar but dispersed ecosystems.
As part of this process several dinosaur species were now evolving and multiplying on different continents. They seem to have been descendants of reptiles and forerunners of birds - scaly at first, but with a few eventually being able to regulate their body temperature, and in the process developing feathers.
Like reptiles and amphibians, they had proportionally small, simple brains and acted mostly by instinct, but their legs were strong enough for them to stand upright and this gave them a distinct advantage.
The first ones were what scientists call lizard-hipped dinosaurs, mostly carnivores running on very strong back legs and using short forelegs to grasp a reptile or amphibian as they killed it with a bite. But soon there were some browsing dinosaurs moving on four legs.
A few of them apparently lived and travelled in groups, but they seem to have been no more than acquaintances, clumping together to present a solid front as protection from the carnivores. They spent most of their time consuming the plants that were all around them.
By now in the forests more primitive trees had given way to cycads, gingkos and early cone-bearing trees (conifers), with tough branches and leaves. Nevertheless the browsing dinosaurs were able to eat and digest them - another example of coevolution.
The new trees put their male and female organs in the centre of a cone, and their male cells in grains of pollen. When the cones opened, some of a male cone’s pollen drifted onto the organ in a nearby female cone. Then the female cone closed up to protect the fertilized seeds as they developed, and later re-opened to release them onto the ground.
Any nearby dinosaur excreta provided a rich fertilizer to aid germination, and there were also enough seeds for some to be consumed by various passing animals.
Some dinosaur families were taking an even more significant evolutionary step. Their females laid fewer eggs than reptiles, and both parents protected, warmed and turned them, and then fed and protected the hatchlings.
Since this behaviour called for a very important new way of knowing and interacting, the hormonal activity that signalled pleasure and pain through their nervous system must have expanded.
A very significant new way of living as an animal had emerged: support of one’s young.
Supporting hatchlings required other kinds of brain expansion in adult dinosaurs. They had to keep them supplied with food, and they also had to keep track of a number of older, mobile, offspring.
So they must have developed an awareness of quantity and number – admittedly very basic by later standards. A rough verbal translation of their processing of quantity might be: ‘Have I got enough for them this time (or do I have to go out again)?’ And of their processing of number: ‘I think there should be more than one of them here.’
Meanwhile a few dinosaurs were leaping across the ground, gliding from tree to tree, and perhaps even flying short distances.
Among them were ancestral birds, with teeth, long bony tails, clawed digits, and primitive wings that may have been used for cooling or gliding rather than flight.
In the early conifer forests as well were the first tiny mammals, most only a few centimeters long and making a living as far out of the way of adult dinosaurs as they could.
Like all other existing land-animals but unlike later mammals, the females still had a cloaca (single cavity) - hence the name of their living descendants: monotremes, literally ‘one hole’. And like all other land-animals apart from some dinosaur species, the adults led a solitary life, with the male joining a female only to mate, and often having to fight off or wear out any other males first.
(Today monotremes are extinct everywhere but in Australia and New Guinea. They include the echidna and the platypus, a cat-sized distant relative of which would appear later in a Gondwanan rainforest – on today’s Lightning Ridge.)
Monotremes differed from reptiles in quite a few ways.
Firstly they were warm-blooded and furred and so they could spend the day asleep in a burrow, coming out to feed and mate at night when most dinosaurs were asleep. Secondly they had efficient smell-sensors that helped them find their way to high protein food as quickly as possible. They ate mostly seeds, insects, eggs and small reptiles, and with a fast metabolism they needed food several times a night.
But the most significant difference was that a mother nurtured her young, and she did it in a surprising new way.
She laid a few fertilized eggs in a burrow, but when her tiny hatchlings emerged they were naked and very immature. She kept them warm, fed them with milk oozing through pores in her soft belly-skin, and protected them from any animals that would regard them as food – until they developed the form and agility they would need to survive on their own.
This nurturing was part of a reproductive cycle coordinated by the hypothalamus, a master-gland evolving as part of a new layer around the pre-programmed brain she inherited from reptiles. (Scientists call this new layer a cortex.)
A monotreme female’s hormones ensured that she came into heat (or oestrus), sent out a ‘Come and get it’ scent, and then tested the fitness of responding males by leading them on a not-so-merry chase. Other hormones later prompted her to protect, nurture and suckle her young.
When a male reached maturity his hypothalamus had a less complex task, co-ordinating hormones that prompted him to respond to a female scent and to compete with other males.
These internal calls for action, most of them particular to a monotreme’s gender, are the basis of our emotions. Since they would develop further with true mammals, it seems clear that a new way of living was emerging: action in response to gendered emotions.
Monotremes were pioneering the sexual specialization that mammals are known for among vertebrate animals, and as part of this process the amygdala began to develop slightly differently in males and females.
Meanwhile some hardy insects like cockroaches were thriving among the plants and other animals. Their descendants would have to adapt very little in order to survive until today (for instance drier conditions led to burrowing and then modified wings).
And they are expected to survive well into the future, no matter what it brings. One of their superior survival strategies is that some of their females keep their eggs inside their bodies until they are ready to hatch, and a few even give birth to fully formed offspring.
Near the ocean-floor were the ancestors of today’s squid, spiral-shelled mollusks whose adult size ranged from a centimetre to two metres in diameter.
During their lives they made strong closely coiled shells, attaching identically proportioned but progressively larger chambers as they grew inside them. They controlled their buoyancy and movement by varying the amount of air and water in the chambers.
Although they were not long-term survivors like cockroaches, their influence would last long after they became extinct. Today they are an iconic example of the various organic patterns that have inspired human ideas of symmetry and rhythm over thousands of years.
(Throughout what is Australia today ammonite fossils of all sizes are commonly found in limestone rocks, formed from the remains of creatures with softer shells.)
Back in our story the supercontinent Gondwana was now beginning to break up. The west coast of Africa was splitting off from the east coast of South America, forming what we call the southern Atlantic Ocean. And India was separate from the western coast of Australia and moving north, creating the Indian Ocean as it went.
A split was opening in Laurasia too, forming the northern Atlantic Ocean between Eurasia and North America.
And the Panthalassa Ocean was contracting into the Pacific Ocean. Of course all these oceans are still really sections of one vast ocean.
(In the areas that would be Australia’s coastline there were great volcanoes along today’s east. And in today’s west, huge lava flows poured up from 100 km below the sea, covering an area of land 200 km wide and 70 metres deep. Several comets and asteroids also hit Australia around this time. One left a 24 kilometre crater at Gosses Bluff, in the Northern Territory. Today it is one of the best-preserved ancient impact sites on Earth.)
In a wonderful greenhouse climate from north to south across Earth, plants with seeds were multiplying and diversifying. Now they included more modern pine-trees, which were creating huge forests everywhere, helped by underground networks of microbes, newly evolved fungi, and earthworms – and also by many insects. And trees, microbes, fungi, earthworms and insects were all thriving.
* * * * * * *
A fossilized ammonite cut in halfto reveal the exquisite pattern of its spiral shell
formed by the animal as it grew larger and larger.
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