Where on earth did insects COME from, anyway? What did they evolve from? Trilobites? Shrimp? Plankton?
Britannica
see Insect Evolution and paleontology - Origin of insects
http://www.britannica.com/bcom/eb/article/0/0,5716,108350+35+105953,00.html
small sample below
The most primitive insects known are found as fossils in rocks of the Middle Devonian Period and lived about 350,000,000 years ago. The bodies of those insects were divided then, as now, into a head bearing one pair of antennae, a thorax with three pairs of legs, and a segmented abdomen. Those insects originated with the terrestrial branch of the phylum Arthropoda. The Arthropoda, whose origin is thus far unknown, probably arose in Precambrian times, perhaps as much as 1,000,000,000 years ago. Some arthropods colonized the open sea and have become the present-day class Crustacea (crabs, shrimps) and the now-extinct Trilobita. Other arthropods colonized the land. This terrestrial line persists chiefly as the classes Onychophora, Arachnida (spiders, scorpions, ticks), the myriapods (consisting of Diplopoda [millipedes], Pauropoda, Symphyla, and Chilopoda, or centipedes), and finally the class Insecta.
The most primitive insects today are found among the wingless (apterous) hexapods; sometimes known collectively as apterygotes, they include proturans, thysanurans, diplurans, and collembolans. It is agreed generally that insects are related most closely to the myriapod group, among which the Symphyla exhibit most of the essential features required for the ancestral insect form (i.e., a Y-shaped epicranial suture, two pairs of maxillae, a single pair of antennae, styli and sacs on the abdominal segments, cerci, and malpighian tubules). There is, therefore, general agreement that the insects probably arose from an early symphylan-like form…
and much more
Astro is right, insects are most closely related to myriapods (incl. centipedes and millipedes). Let’s see if this works:
Insects Myriapods Chelic. Trilo.(ex.) Crust.
| | | | |
------------- | | |
| | | |
Unirames | --------------
| | |?
| ------------------
| |
-------------------------
|
Onchyophoran-like ancestor
|
to Onchyophorans?<-----
|
Lost in antiquity, but connected to Annelids and Molluscs
This tree is reconstructed from a 1997 invertebrates class. If someone would like to come along and update/correct it, please do so. I don’t know how old the Britannica article is, but my invert. zoo. text (Ruppert and Barnes, 1994. Invertebrate Zoology) classifies the Onchyophorans in their own phylum, but these ancient relationships are unclear. Symphylans, which are thought to be similar to ancestral unirames, are little centipedes (about 1-8 mm) with a dozen legged segments, with insect-like mouthparts and posterior to the legs, small sensory hairs and a telson.
Oops, that didn’t work. Sorry.
OK, working backwards using The Tree of Life page as a reference. This is a cladist look at the branching order.
The hexapoda, insects, springtails, diplurans, and proturans all came from a common ancestor. Hexapods and the myriapods (millipedes, centipedes and the likes) share a common ancestor that shares a common ancestor with the rest of the arthropods. It gets increadibly complicated past that, but they are related most closely to the velvet worm and water bears and a little less closely to segmented worms and the likes. Check out the web page and root around, you’ll eventually find out what you’re looking for and far, far, far more.
Nest it in [code].
*Originally posted by wevets *
**Astro is right, insects are most closely related to myriapods (incl. centipedes and millipedes). Let's see if this works:
Insects Myriapods Chelic. Trilo.(ex.) Crust.
| | | | |
------------- | | |
| | | |
Unirames | --------------
| | |?
| ------------------
| |
-------------------------
|
Onchyophoran-like ancestor
|
to Onchyophorans?<-----
|
Lost in antiquity, but connected to Annelids and Molluscs
This tree is reconstructed from a 1997 invertebrates class. If someone would like to come along and update/correct it, please do so. I don't know how old the Britannica article is, but my invert. zoo. text (Ruppert and Barnes, 1994. *Invertebrate Zoology*) classifies the Onchyophorans in their own phylum, but these ancient relationships are unclear. Symphylans, which are thought to be similar to ancestral unirames, are little centipedes (about 1-8 mm) with a dozen legged segments, with insect-like mouthparts and posterior to the legs, small sensory hairs and a telson.**