Evolution of intelligent drepanosaurs

Question

For a story I require an intelligent [drepanosaur]. But to work with the plot the creature needs to still have traits that don't mix well with classical vertebrate evolution of intelligence.

Requirements

• Need them to be on an almost pure insect diet, while being 8 feet tall (not including the tail), and have high functioning brains (average IQ of 120).

• Need to be bipedal with a large (5ft), muscular, hooked, prehensile tail.

• Need to reproduce slowly.

• Need a reason for them to have been in an isolated environment that kept their intelligence from letting them spread out on the earth and invent things until they escaped the place.

• All these reasons can't mess up Earth's history too much, I still need modern America as a setting.

Question

So what changes/reasons could be used to make this evolutionary path possible?

Answer 1

The general route will be based on human evolution: During a period of reduced forestation some groups of drepanosaurids adapted to a lifestyle among the grass-ferns of central Pangea.

On these Pangean savannahs live the giant social titanoptera. They had evolved a eusocial form, similar to termites or ants, but larger: workers are 2-5 centimetres long (depending on species), and they build large "castles". The drepanosaurs first developed tool use to get inside these castles. The growth in size was in response to the difficulty of breaking into a titanoptera castle. The development of bipedalism allow the front feet to become hands and made complex tool development possible. The large amount of food energy available from eating these insects allows for brain development. They are now highly dependent on these insects, and until the development of farming they were limited to the regions where the social titanoptera lived.

An evolutionary arms race developed, with the titanoptera making ever more well-defended castles, and the drepanosaurids responding with more complex tool use. Modern drepanosaurs now farm titanoptera, and the development of domesticated varieties has greatly changed how modern drepanosaurs live, but this is a recent development.

Sexual selection played a major role in the development of the intelligent drepanosaurids. The tail, which had been important for climbing when they were in the trees, became a major secondary sexual organ. Its general condition, strength and dexterity being considered highly desirable by both sexes. Another interesting aspect of their behaviour is the courtship challenge. Members of both sexes will set complex tasks for the other to accomplish. This sort of flirting is nearly always seen prior to forming a pair bond, the tasks often require a combination of memory, puzzle solving and physical dexterity (often but not always involving the tail). Young drepanosaurids will spend a lot of their free time practising solving puzzles or playing games of skill in the hope of becoming more attractive.

So we have a group of large bipedal archosaurs with muscular tails and high intelligence that were restricted to a particular environment by their narrow diet.

Answer 2

Ideas:

1: Time travelers.. These residents of the Triassic were intelligent in their own time, but went extinct. Through some plot device, a population travels through time and visits your story. Dimensional travelers (from alternate earth where dinosaurs did not go extinct) would work this way too.

2: Alien uplift. Aliens visiting the ancient earth were enamored of the drepanosaurs and took a population with. Over the ensuing years the drepanosaur pets and then companions of these aliens evolved intelligence and other aspect which lend themselves to your story. It is a population of these expatriates who visit your story.

3: Hollow earth. Frank Frazetta firmly established that Pellucidar is full of dinosaurs, ancient mammals, pterosaurs and amazingly attractive fur clad savage folks. Probably intelligent drepanosaurs too! I bet they rule the place. Skull Island / Land that Time Forgot / Valley of the Dinosaurs etc are all along these lines, but Hollow Earth is the best.

4: Valusians. It is hard to be an intelligent race of reptilians sharing the earth with humans. You need some tricks. Your intelligent (and conniving!) drepanosaurs live among humans and hide in plain sight, using their technology / magic. They do not invent things because they want to keep a low profile. Robert Howard had some like this in the Kull stories.

https://en.wikipedia.org/wiki/The_Shadow_Kingdom

Brule reveals that the Serpent Men, an ancient pre-human race that had built Valusia but was almost extinct, ruled from the shadows, using their Snake Cult religion and ability to disguise themselves with magic. They intended to replace Kull with a disguised Serpent Man, just as they had done with his predecessors.

Answer 3

Intelligence is Rare, and hard to evolve

Unfortunately evidence (ie. life on Earth) indicates intelligence is not inevitable.

The dinosaurs have been on this planet for 250 million years, and they never developed farming, cities, and technology.

Prior to that there were many billions of years where life existed, yet intelligent life capable of consistent invention, has not occurred.

Also, we have had the same brain size for quite some time (in fact, Neanderthals had larger brains than us), yet intelligence enough to 'invent things' is only evident in the last 40,000 years, when the secret of fire is discovered, or when farming was used. And that's when we were already on the planet for over 1.8 million years.

So why is this?

It is probably ironic, but it may be that our deficiencies as a species is a major factor in our intelligence, combined with extraordinary luck and being in the right place at the right time.

We have laughable attributes - we don't have much fur, don't run very fast, our digestive systems are fussy, our jaws and teeth not like predators, and our children are difficult to bring up and require inordinate resources. Yet, necessity is the mother of invention, and it may be that these deficiencies caused us to invent fire to keep warm eventually during the last ice age, use tools to defeat predators and be safe, have intricate social structures to protect vulnerable children, breed plants to farm crops to eat comfortably, and basically a very ponderous and slow trial and error process occurs through invention.

So in other words, the attributes of your archosaur may be insufficient to develop intelligence, and it may be too good at what it does to really need to develop social structures and trial and error technology. In a way, it may just be sheer luck that it develops intelligence enough to embark on invention, with the help of a lot of adversity.