In Jain Dharma, this kind of “mapping” has to be answered very carefully, because:

• Jain time (kālchakra) is beginningless and cyclical, with unimaginably huge numbers.
• Modern science uses linear physical time (billions of years, geological eras, evolution, etc.).
• Our scriptures do not talk about “dinosaurs”, “Homo erectus”, or “first life” in the scientific sense.

So we can explain what Jain texts say, and we can state what science says, but we cannot truly line them up exactly. At best we can say “this would lie somewhere in extremely remote, previous cycles” etc.

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1. “What era was it when Jain was founded?”

From a Jain point of view:

• Jain Dharma has no founder and no starting date.

It is anādi–ananta – beginningless and endless.

• In every time-cycle there are Tirthankars who re-discover and re-teach the same eternal Dharma.

In the current Avasarpiṇī (descending half‑cycle) in our Bhārat Kṣetra:

• There are 24 Tirthankars.
• They appear between the 3rd and 4th āra (era).
• Bhagwān Mahāvīr lived at the very end of the 4th āra (duḥṣamā‑suṣamā) and attained nirvāṇa at its close.
• After his nirvāṇa, the 5th āra (duḥṣamā) began. We are living in this 5th āra now. ( jainknowledge.com)

So:

• Jain Dharma itself: no “founding era”, it is eternal.
• The current form of Jain Sangh based on Mahāvīr’s teachings:

belongs to the end of 4th āra of Avasarpiṇī.

You can read a simple overview of the eras (ārās) and the time cycle here:

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2. Era of the first signs of life on earth

What modern science says (very briefly)

• First life: roughly 3.5–4 billion years ago, in what geologists call the Archean eon.
• Earth itself is about 4.5 billion years old.

What Jain Dharma says

Jain scriptures do not give a one‑time “birth of life”:

• Life (jīva) is also beginningless.
• There have always been living beings in some part of the loka (universe).
• Each half‑cycle (Avasarpiṇī / Utsarpiṇī) has immeasurably long durations for its first eras (e.g. sukhama‑sukhama etc.), running into sāgaropama and asankhyāta years (innumerable). ( jainknowledge.com)

From a Jain standpoint, “first life on earth” in the scientific sense would not be fixed to any specific āra of the present Avasarpiṇī; rather:

• Such events would lie far back in unimaginably remote portions of the overall eternal cycles, not as a single creation moment.

So: Jain texts do not give a specific era/āra for “first life”, and it cannot be rigorously calculated from our current 5th āra.

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3. Era when Homo erectus (early humans) appeared

What modern science says

• Homo erectus appears in the fossil record roughly 2 million years ago, long before today’s Homo sapiens civilizations.

Jain perspective

Jain cosmology:

• Speaks of human beings (manuṣya) with very variable heights and lifespans depending on the āra:

- In early happy eras, humans are extremely tall and live for palyopama spans. - In the present 5th āra, lifespans are short (decades) and dharma is in decline. ( jainknowledge.com)

• Does not describe evolution in terms of species like “Homo erectus”, “Homo sapiens”, etc.
• Does not give a fossil‑style history that you can line up with 2 million years ago.

Also note: in Jain cosmology:

• The 5th āra of Avasarpiṇī is only 21,000 years long in total, and only about 2,500–2,600 years of it have passed since Mahāvīr’s nirvāṇa. ( jainknowledge.com)

So a scientific event 2,000,000 years ago:

• Cannot fit inside our present 5th āra.
• Would belong (if you try to relate it at all) to some extremely earlier stretch of the cosmic cycles, not something our texts calculate or name by āra.

Therefore: Jain scriptures do not specify an āra or time‑cycle position for “Homo erectus”.

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4. Era when dinosaurs first walked on earth

What modern science says

• Dinosaurs dominated the Mesozoic Era (~252 to 66 million years ago).
• The earliest dinosaurs appear over 230 million years ago.

Jain perspective

Again, our āras in the current Avasarpiṇī:

• 1st & 2nd: incredibly long, sāgaropama / asankhyāta periods of great happiness.
• 3rd, 4th, 5th, 6th: progressively shorter (thousands to tens of thousands of years in this cycle). ( jainknowledge.com)

The “dinosaur age” of science, tens or hundreds of millions of years ago:

• Is not explicitly mentioned in Jain scriptures.
• Cannot be placed within any named āra of our current Avasarpiṇī by scriptural calculation.
• If you insist on relating the ideas at all, it would lie somewhere in the vast, repeated, earlier cycles of time, not something tradition has tried to map.

So: There is no authoritative Jain assignment like “dinosaurs lived in such‑and‑such āra of Avasarpiṇī/Utsarpiṇī”. That is simply not how our Acharyas have presented kālachakra.

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5. Why we cannot really calculate these things from Avasarpiṇī

You mentioned:

> we should be able to calculate during which era these events happened based on the time periods of how the avasarpini works and what era we are currently in?

From a traditional Jain standpoint, this is not actually possible, because:

1. Āra durations are:

- Symbolically and unimaginably large in the first eras. - Given in units (sāgaropama, palyopama, asankhyāta) that do not match modern “years” directly.

1. Time is cyclical and beginningless:

- There have been endless previous Avasarpiṇīs and Utsarpiṇīs. - Life and human forms have appeared and disappeared in countless cycles.

1. Scriptures never try to line up:

- No Jain āgama or classic cosmology text says, “In this āra, 3.5 billion years after X, first life appeared,” or “Dinosaurs lived in the Nth āra 250 million years ago.” - Those are modern scientific reconstructions, outside the scope of śāstra‑pramāṇa.

So a faithful Jain answer is:

• We can state which āra we are currently in (5th āra of Avasarpiṇī in Bhārat Kṣetra).
• We can state when Mahāvīr lived relative to the āras (end of 4th āra).
• But for “first life”, “Homo erectus”, “dinosaurs”, we cannot assign precise Jain eras from scripture.

At most we can say: such physical events, if accepted, belong to some remote, past parts of the eternal time‑cycle, not to any dated ara we know by calculation.

For a simple intro to the cyclical nature of time in Jainism: