Deep time

Arthropod evolutionary history

Every lineage in the T-Hawk portfolio has been iterating on its venom since before the first tree. This is the record of that R&D program.

How to read this. Scorpions have been refining venom for roughly 435 million years; spiders for 380; the aculeate wasps and ants in the T-Hawk portfolio are younger, and radiated after flowering plants did. Different ages mean different chemistries, and independent origins mean that when two of these bars converge on the same human drug target, they arrived there separately.
Geological Timeline
Arthropod evolutionary timeline Horizontal bar chart showing origin and extent of major arthropod lineages from 540 Ma to present, with mass extinction markers Cambrian Ord–Sil Devonian Carboniferous Permian Triassic Jurassic Cretaceous Cenozoic 540 500 450 400 350 300 250 200 150 100 66 0 Ma millions of years ago (Ma) P–T 252 Ma K–Pg 66 Ma Arthropoda (ancestor) Chelicerata Mandibulata Scorpions 435 Ma Marine ~435 Ma → land ~400 Ma → highly conserved to present Centipedes 430 Ma Silurian land colonizers; apex predators in early terrestrial ecosystems Spiders 380 Ma First chelicerate silk ~380 Ma; orb-weaver revolution ~200 Ma; tarantulas: deep Mygalomorphae lineage Insects 412 Ma First hexapods ~412 Ma; flight ~325 Ma; Holometabola ~310 Ma; ≥1M described species Hymenoptera 280 Ma Sawflies ~280 Ma; Aculeata ~165 Ma; bees ~130 Ma; eusociality ~100 Ma; post K–Pg explosion
Lineage Profiles

Scorpiones: Scorpions

Chelicerata · ~2,600 extant species
Origin: ~435 Ma (Silurian)  |  Land colonization: ~400 Ma
  • ~435 Ma

    Marine scorpions appear

    Fully aquatic, gill-bearing forms in Silurian seas. Modern body plan (chelicerae, pedipalps, metasoma, telson with venom gland) already present. Remarkable conservatism to present day.

  • ~400 Ma

    Terrestrial colonization

    Book lungs derived from aquatic book gills. Waterproof cuticle, nocturnality, and burrowing behavior enable arid-environment dominance.

  • ~320 Ma

    Venom apparatus refinement

    Vesicle + aculeus system functionally identical to modern forms by Carboniferous. Divergent evolution of ion-channel toxins (NaV, KV subtypes) begins.

  • Present

    ~2,600 species; Arizona focus

    Arizona's desert scorpions retain the full ancestral venom architecture. Their sodium- and potassium-channel-active peptides are among the most extensively studied in venom pharmacology, and remain the reference point for ion channel selectivity.

Chilopoda: Centipedes

Myriapoda · ~3,300 extant species
Origin: ~430 Ma (Silurian)
  • ~430 Ma

    First myriapods on land

    Among the earliest confirmed terrestrial animals. Apex predators in Silurian–Devonian plant-litter communities.

  • ~300 Ma

    Carboniferous giant forms

    Hyperoxic atmosphere (~35% O₂) permitted giant arthropods. Arthropleurid relatives reached 2.5 m. Size reduction followed Permian O₂ decline.

  • Present

    Forcipule-delivered venom

    Centipede venom is delivered through forcipules, modified front legs rather than mouthparts. Sonoran Desert species carry a mixed venom of biogenic amines, cardioactive peptides, and ion-channel-active proteins.

Araneae: Spiders

Chelicerata · ~50,000 extant species
Origin: ~380 Ma (Devonian)
  • ~380 Ma

    First true spiders

    Attercopus fimbriunguis: earliest confirmed spider with functional silk spigots. Segmented abdomen retained; unsegmented opisthosoma is a later synapomorphy.

  • ~300 Ma

    Mygalomorphae diverge

    Two-lunged "primitive" spiders: tarantulas, funnel-webs, trapdoor spiders. Ancient venom chemistry rich in polyamine toxins and peptide neurotoxins; primary drug-discovery scaffold lineage.

  • ~200 Ma

    Orb-weaver silk revolution

    Silk protein gene diversification enables aerial capture webs. Directly tied to flying-insect prey diversification.

  • Present

    Arizona tarantula lineages

    Theraphosid venoms are dominated by cysteine-rich inhibitor cystine knot peptides: compact, protease-resistant scaffolds that act on ion channels with high selectivity. The Sonoran Desert species are almost entirely uncharacterized.

Insecta: Insects

Hexapoda · ~1,000,000+ described species
Origin: ~412 Ma (Devonian)
  • ~412 Ma

    First hexapods

    Rhyniognatha hirsti (Rhynie Chert, Scotland). Early insects were wingless soil/leaf-litter inhabitants.

  • ~325 Ma

    Origin of flight

    Most transformative innovation in arthropod history. Coal-forest canopy opens as entirely new ecological dimension. Dragonfly relatives reached 70 cm wingspan.

  • ~310 Ma

    Holometabola: complete metamorphosis

    Larva–pupa–adult lifecycle eliminates intraspecific competition. Holometabola constitute ~80% of all insect and ~60% of all animal species.

  • ~252 Ma

    P–T extinction survival

    Fewer than 10 family-level insect losses despite 96% marine species extinction. Small size, short generations, and terrestrial habitat conferred resilience.

Hymenoptera: Ants, Bees, Wasps, Sawflies

Holometabola · ~150,000 described species
Origin: ~280 Ma (Permian)
  • ~280 Ma

    Hymenoptera origin

    Basal sawflies (Symphyta) were plant feeders, inserting eggs into plant tissue via ovipositor. Defined by membranous wing venation and, in advanced forms, the petiole ("wasp waist").

  • ~240 Ma

    Parasitoid lifestyle

    Ovipositor co-opted for drilling into arthropod hosts and injecting paralytic venom. Estimated 10–20% of all insect species are parasitoid Hymenoptera, an extraordinary speciation driver.

  • ~165 Ma

    Aculeata: the sting evolves

    Ovipositor loses egg-laying function in worker females; becomes a sting. Enables colonial defense, active prey hunting, and sophisticated chemical communication.

  • ~130 Ma

    Bees emerge from wasps

    Monophyletic clade from within hunting wasps, switching from animal prey to pollen provisioning. Tight co-evolution with angiosperm radiation. Bee venom: melittin + PLA₂ are now most-studied venom proteins in pharmacology.

  • ~100 Ma

    Eusociality confirmed

    Sphecomyrma in Burmese amber (~92 Ma): clear queen–worker dimorphism. Haplodiploid sex determination (sisters related at r=0.75) predisposes order to eusociality per Hamilton's rule.

  • ~25 Ma

    Pompilid wasp radiation

    Spider-hunting wasps diversify alongside the mygalomorph spiders they hunt. Their venoms evolve toward rapid, precise paralysis of prey many times their own mass: short, fast-acting peptides rather than tissue-destroying enzymes. This venom chemistry is exceptionally poorly characterized worldwide.

Mass Extinctions: Arthropod Impact Summary
Event Ma Severity Arthropod / Insect Impact
End-Ordovician ~443 Major ~85% marine species lost; early terrestrial myriapods and chelicerates largely unaffected
Late Devonian ~374 Major Severe marine crisis; terrestrial arthropod communities emerging in Devonian survived with modest losses
Permian–Triassic (P–T) ~252 Critical ~96% marine species lost; insects had remarkably low family-level extinction rate (<10 families). Terrestrial habitat acted as refuge.
End-Triassic ~201 Major Modest insect impact; opened niches exploited by rapid Jurassic diversification of flying insects and early Hymenoptera
Cretaceous–Paleogene (K–Pg) ~66 Critical Dinosaur extinction; angiosperms rapidly rebounded → bee and ant diversity exploded through Paleocene–Eocene. Paradoxically beneficial for Hymenoptera.