TST Evolution: Animals

Go To: Cephlapods | Insects | Fish | Amphibians | Reptiles | Dinosaurs & Birds | Synapsids & Mammals

By 555 million years ago, animals emerge. The comb jellyfish is likely the first true animal. Originally, we thought simple simple sponges evolved first, but genetic analyses changed that.

Prokaryotic Life

3.73 Billion Years Ago (after LUCA)

Membrane and metabolic diversity.

Archaea Diverge

3.73 Billion Years Ago (shortly after LUCA)

Ether-linked membranes and distinct genetic machinery

Touch: Life Learns to Feel Force

~3.72 Billion Years Ago (after prokaryotes)

Mechanical sensitivity to pressure and membrane stretch

The First True Eukaryotes

2.4 Billion Years Ago (+/- 300 million years)

Bacterial Endosymbiosis: Origin of Eukaryotes

~2.4 Billion years ago (+/- 100 million)

Bacteria are added to eukaryote ancestor cells

Protozoa Evolve

2 Billion Years Ago (+/- 100 million years)

Nucleus and internal organelles

LECA: Likely Sexual Reproduction

~1.75 billion years ago (+/- 50 million)

Last Eukaryote Common Ancestor

Unikonts: Single-Motor flagella Reform

~1.3 Billion Years Ago (+/- 100 million)

Transition to a Single Flagellum

Intracellular Flow and Nutrient Exchange

~1.2 Billion Years Ago (+/- 300 million)

Cytoplasmic streaming and vesicle transport

Opisthokonts: True Posterior Flagellum

~1.15 Billion Years Ago (+/- 50 million)

12 unique amino acids + glycogen energy storage + True Posterior Flagellum

Oogamy: Early Gamete Specialization Before Animals

~1.1 Billion Years Ago (inferred, +/- 100 million)

Small motile gamete and larger nutrient-rich gamete

Animal Ancestors Split Off: Cadherin Cell Glue (Holozoa)

~750 Million Years Ago (+/- 50 million)

First Multicellular Animals

640 Million Years Ago (+/- 20 million)

Stable cell adhesion and tissue specialization

Presentient Animals Emerge: The Ediacaran Prelude

635-600 Million Years Ago

Proto-brain; Pre-brain memory; Presentient.

First Animal Egg Layers

~620 Million Years Ago (+/- 20 million)

tissue-level reproduction

Chemoreception: Taste and Smell Emerge

600 Mya

First True Animals – Comb Jellyfish

555 Million Years Ago (+/- 5 million)

Nerve nets and muscle cells

Internal Fluid Transport in Early Animals

~550 Million Years Ago (+/- 25 million)

Diffusion and body-cavity circulation

True Circulatory Systems: Blood Veins

545 Million Years Ago (after through-gut digestion: mouth/anus)

Circulatory fluid transport (veins)

Vision Emerges: The Pre-fish Chordates

540 Mya

Vision Emerges; Proto-Simple Brains; Pre-vertebrate Cord.

First Vertebrates

530 Million BCE

530 to 520 Million Years Ago

Earliest Known Hunter

520 Million Years Ago

First Simple Brains; Proto-Short-Term Memory; Simple Sentience.

Simple Sentience Settles: Haikouichthys

520 Million BCE

Simple Brains; Proto-Short-Term Memory; Simple Sentience.

Simple Cephalopod Sentience Evolves

510 Million BCE

Not a fish ancestor, not our ancestor.

Keratin Genes & the Rise of Scales in Fish

425 Million Years Ago

425 MYA (+/- 15 Million Years)

Oldest Known Air Breather

414 Million BCE

Lungs Evolve: Lobe-Finned Fish and the Lungfish Ancestor

400 Million BCE

The Senegal Bichir: A Living Fossil

~380 million years ago (± 15 million)

Air breathing lungs and lobed pectoral fins

Long-Term Memory Evolves: Tiktaalik

375 Mya

Complex Brains; Long-Term Memory; Simple Sentience.

Land Hearing Emerges: Amphibians

370 Mya

Land Hearing Emerges; Yet Larger Brains.

Reptile Amniotic Eggs

318 Million BCE

First Land Herbivore: Tyrannoroter heberti

307 million years ago

2026 Discovery Pushing Back Herbivores

Stem Selachians: Modern Sharks LCA

~300 million years ago (± 10 million years)

Proto-Play

300 million years ago

±20 million years

Early Complex Sentience Emerges: Dimetrodon

295 Million BCE

Complex Brains; Long-Term Memory; Early Complex Sentience.

Dinosauromorphs Emerge: Asilisaurus kongwe

245 Million Years Ago

Erect hind-limb posture

Nyasasaurus parringtoni

243 Million Years Ago

Strengthened hip and shoulder architecture

XX/XY Sex System Emerges: A Tale of Mammalian Evolution

240 Million Years Ago

Marasuchus lilloensis

240 Million Years Ago

Elongated hind limbs, better running, reduced forelimbs

First True Dinosaur: Eoraptor lunensis.

229 Million Years Ago (± 1.5 million)

Fully open hip socket (perforated acetabulum)

Platypus–Ape Common Ancestor

225 million years ago (±5 million years)

When dinosaurs rose, our line quietly began.

Morganucodon: An Early Mammalian

203 Million BCE (+/- 3 million)

Differentiated teeth and true mammalian jaw

Early Play Evolves in Mammals

190 Million Years Ago (+/- 10 million years)

Parental care, brain plasticity, extended juvenile period

Mammals: First Live Births

185 Million BCE

Placental nutrient transfer (in placentals)

Complex Sentience Settles: Eomaia scansoria

circa 125 Million BCE

Complex Brains; Long-Term Memory; Complex Sentience; Likely Proto Self-aware.

Animal Vocabulary: Dozens of Words

125 Million Years Ago

Expanded Limbic System, reward circuitry

Appendix

80 Million BCE

Higher Play Evolves in Social Mammals

80 Million Years Ago (+/- 10 million years)

Enlarged neocortex

Purgatorius — Earliest known proto-primate.

66 Million BCE

Grasping hand and flexible ankles

Opposable Thumb Emerges

60 Million Years Ago

Plesiadapis: First fruit-insect eaters.

56 Million BCE (+/- 2 million)

Enhanced color perception, Diet-driven brain growth

Early Self-Awareness: Miacis

50 Million BCE

Territory memory, where things are, hippocampus development

Ape Thumb Evolves

32 Million Years Ago (+/- 2 million)

Early Intelligence Emerges: Aegyptopithecus zeuxis

30 Million BCE

Complex Brains; Long-Term Memory; Complex Sentience; Semi Self-awareness settles in.

Baboons Branch Off: Old World Monkeys

27 Million Years Ago (+/- 2 million)

Large neocortex, Coalition politics emerge

Genus Proconsul (Self-Awareness Settles)

20 Million Year Ago (+/- 2 Million Years)

Complex Brains; Long-Term Memory; Complex Sentience; Maybe Self-aware; Likely Simple EI.

Gibbons Branch Off: Genus Hylobates

17 Million Years Ago, ± 1 million

Long-distance pair bonding, Fine motor control

Animal Vocabulary: Thousands of Words (The Great Apes)

circa 15 Million Years Ago

Inferior frontal gyrus homologues, Mirror neuron systems

Orangutans Branch Off: Genus Sivapithecus

Emerged 12.5 to 12 mya, extinct 8.5 to 7 mya.

Complex Brains; Long-Term Memory; Complex Sentience; Self-aware; Complex EI.

Gorillas Branch Off: Genus Nakalipithecus

Emerged 10 mya, extinct 9.8 to 9 mya.

Ancestral Hominids (us, pre-split)

Emergence of the Chimpanzee Family

2 Million BCE

Hominids, Not Us (different branch)

Genus Orangutans

400,000 Years Ago