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Life Without Vertebrates; *OP updated*
Topic Started: Dec 24 2009, 04:12 PM (2,288 Views)
KayKay
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This will be an open project, anyone can join in to give their input and ideas.

This is a time line where a major extinction event early in Earth's history wipes out all vertebrate life on the planet, and many invertebrates along with them. Life Without Vertebrates is actually going to see the loss of all chordates. This will happen at the transition between the Devonian and the Carboniferous (if anyone thinks another point in history would be better, feel free to speak out).

The remaining invertebrates take the place of vertebrates and dominate the sea and land.

The mass extinction that causes this will have to be tailored to give vertebrates the hardest time. It must also be very severe, to be able to wipe out every single last chordate, so there would be a loss of many invertebrates too. Which invertebrates die out will depend upon the extinction event.

1. Decide what the extinction event will be, and how it will affect the climate. It must allow a significant number of invertebrates to survive, but wipe out all chordates.

2. Find out all of the known invertebrates that existed during the Late Devonian and Early Carboniferous, preferably as close to just before the extinction event as possible, and preferably species where there is adequate information available.

3. Decide which invertebrate species will survive, and mark out basic food webs for all of the major climate zones of the surviving invertebrates after the aftermath.

This will provide a starting point for the project.

So... first an extinction event suited for wiping out vertebrates and allowing enough invertebrates to live... Any ideas? If anyone wants to move on to the other steps that's fine, they were just a guideline anyway.

EDIT:

what we have so far....

A disease spreads that attacks chordates. Chordate species numbers plummet, but some chordates and a minimal number of vertebrates survive. Soon after, a meteorite impact on the main equilateral continent wipes out a large portion of both invertebrates and vertebrates. Many invertebrates make it through, but vertebrates are already dying out so the impact brings them down to critical numbers. After this point, vertebrate species are too low to ever recover, and they are gradually phased out by invertebrates.

Extinct

All vertebrates

Survivors

Arachnids
Trilobites
Centipede relatives (looking for names to be more specific)

Onychophora

Nautiloids *
Ammonoids *
Orthocerids *

*Could one of them become squid analogues?

Archaeopteris (spore-bearing)

Considering

Marine arachnids (to replace eurypterids) *
Marine scorpions (to replace eurypterids) *
Eurypterids (should they live or die off?) *

*Did eurypterids survive to the carboniferous? Would they survive the impact?

Squid, possibly land squid (maybe leave this idea for later on when cephalopods are more evolved)
Edited by KayKay, Dec 28 2009, 02:24 PM.
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Canis Lupis
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Dinosaurs eat man, woman inherits the Earth.

Yes, the same case would definantly occur here. If we were just saying "What if an asteroid struck in the mid-Devonian?", most placoderms would be gone.

But since verts are gone anyway, we've pretty much dealt a blow to some of the marine predators.

Killing off eurypterids, based on my limited prehistoric understanding, would kill off a vast majority of the top marine predators at that time.
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Holben
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Rumbo a la Victoria

Well, i think they were more than that. I think they were dominant, and there would be herbivore blooms, causing mass extinction.

Also, they should have had staying power. They survived many extinctions.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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KayKay
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Hi, I've been working a lot on my notes page. I have made extra notes about Late Devonian species, and in some a few notes about their possible survival of the extinction. What do you think? I'll be doing more searching on Early Carboniferous animals.


Echinoderms:

Echinoids (sea urchins): Archaeocidaris - Information: http://www.nhm.ac.uk/research-curation/research/projects/echinoid-directory/taxa/taxon.jsp?id=54
* First appeared Late Devonian, can it break through the extinction?
Crinoids (feather-stars): Image of one genus, Cupressocrinites: http://www.dkimages.com/discover/DKIMAGES/Discover/previews/989/45007439.JPG, Image and description of genus Cyathocrinites: "Description: A well-preserved example of an Inadunate Cladid crinoid known as Cyathocrinites harrodi (Family Cyathocrinitidae). Its serially branching arms formed a most effective basket for filtering out the minute particles upon which it fed. This one has an attached stem, making it a more desirable example than many seen" Image: http://www.fossilmall.com/EDCOPE_Enterprises/echinoderms/crinoids51/crinoids-51b.htm
* Have survived massive impacts in our time-line.
* Were diverse.

Branchiopoda (Usually fresh water shrimp): Asmussia - Image of generalized clam shrimp: http://www.fettes.com/orkney/Fossils/Images/Arthropod.jpg "This tiny branchiopod crustacean can be found in all Devonian sediments, and indicates a shallow water environment. It is common in the Upper Stromness and Rousay Flagstone group. Depending on the type of sediment and the conditions of fossilization Asmussia murchisoniana shows as a tiny (few mm) thin valve often with growth lines (concentric rings) visible. The crustacean belongs to the conchostracans or commonly called clam shrimps (the shrimp is housed between to chitin valves). Conchostracans occur on all continents and have a full range from the Palaeozoic up to recent time. They are filter feeders but also scrape and tear their food and scavenge on all organisms in their environment. They live in temporary pools or other shallow water conditions."
* Still can't tell if fresh water or salt water - possibility of both.
* Could they survive? Their relatives have survived extinction events up to present day.

Brachiopods (Appearance of bivalves, but not related): Atrypa - Information: http://www.palaeos.com/Invertebrates/Lophotrochozoa/Brachiopoda/Atrypidida.html Terebratula another example.
* Another group that has survived hardships, perhaps they will make it through this event also?

Bivalves: Aviculopecten - Image: http://upload.wikimedia.org/wikipedia/commons/4/4f/Aviculopecten_subcardiformis01.JPG Wilkingia another example.
* Little information on specific species
* Still confident bivalves in general will make it through.


Nautiloids:

Actinocerida: Example, Ormoceras - http://www.yale.edu/ypmip/taxon/ceph/38064sm.gif

Orthocerids: Geisonoceratidae - Squid-like orthocerids with long straight to slightly curved shells. Example: Michelinoceras Image: http://crnmac1.physics.uiowa.edu/fossils/Midwest_Cephalopods/IA_03/Michelinoceras_2.jpg Orthoceras Info: http://en.wikipedia.org/wiki/Orthoceras
* Likely scavengers to predators, could be wiped out.
* Thought to be quite diverse, perhaps some may scrape through?
Pseudorthoceratidae: A member of Orthoceratoidae. Very similar to orthocerids. http://en.wikipedia.org/wiki/Pseudorthoceratidae
* Survived up to 209.5 mya according to the article. Could they survive a meteorite impact?
* Possible predators. Maybe only the most opportunistic with the most varied diet could survive.

Ammonoids: Agoniatidia - Image: http://upload.wikimedia.org/wikipedia/commons/e/ef/Siphuncle.gif 409.1—360.7 mya
"Agoniatitida are primitive ammonoids with a ventral retrochoanitic siphuncle (septal necks point to the rear) reflective of their nautiloid ancestors.and goniatitic sutures with a variable number of lobes. Shells vary from discoidal to globular. Coiling may be loose with whorls barely touching or tight with a dorsal impression."
* Thought to have lived up until the extinction event, will they pass through?

Arthropods:

Eurypterids: Large predator. Low chance of survival.

Trilobites: One example,
Cyphaspis (little info available) Image: http://upload.wikimedia.org/wikipedia/commons/a/a1/CyphaspisPlate.jpg
* Information is sparse.
* Found in Late Devonian.

Scorpions: Example: Palaeophonus - http://en.wikipedia.org/wiki/Palaeophonus virtually identical to modern scorpions, a form too successful to be wiped out by a moderate meteorite. In for sure.

Springtails: Rhyniella praecursor - http://en.wikipedia.org/wiki/Rhyniella_praecursor http://www.abdn.ac.uk/rhynie/collembolan.htm
* Successful, has changed little over hundreds of millions of years. Enough to survive?
Edited by KayKay, Dec 30 2009, 01:06 PM.
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Vultur-10


Land squid as such may be unlikely (since squid are already pretty well adapted to doing what they do) but mollusks will probably be one of the stronger contenders for dominance of land. Both gastropods (there are some land-living ones even on our Earth; slugs and snails) and cephalopods (presumably fairly unspecialized ones, possibly from before the octopus/squid split, might adapt to shallow waters, then swamp/wetland, then eventually land).

The other big contender would be the arthropods. In the absence of vertebrate competition they might get surprisingly large; some of the Carboniferous types like Arthropleura were quite impressive, and even in the modern day coconut crabs are enormous.

I would kind of like to not kill off *all* eurypterids, just most, so we could have a small coastal type survive and maybe found a really weird land (or at least wetland/shoreline) arthropod lineage.
Edited by Vultur-10, Jan 9 2010, 10:18 PM.
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chillypaz2010
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KayKay
Dec 30 2009, 01:04 PM
Hi, I've been working a lot on my notes page. I have made extra notes about Late Devonian species, and in some a few notes about their possible survival of the extinction. What do you think? I'll be doing more searching on Early Carboniferous animals.


Echinoderms:

Echinoids (sea urchins): Archaeocidaris - Information: http://www.nhm.ac.uk/research-curation/research/projects/echinoid-directory/taxa/taxon.jsp?id=54
* First appeared Late Devonian, can it break through the extinction?
Crinoids (feather-stars): Image of one genus, Cupressocrinites: http://www.dkimages.com/discover/DKIMAGES/Discover/previews/989/45007439.JPG, Image and description of genus Cyathocrinites: "Description: A well-preserved example of an Inadunate Cladid crinoid known as Cyathocrinites harrodi (Family Cyathocrinitidae). Its serially branching arms formed a most effective basket for filtering out the minute particles upon which it fed. This one has an attached stem, making it a more desirable example than many seen" Image: http://www.fossilmall.com/EDCOPE_Enterprises/echinoderms/crinoids51/crinoids-51b.htm
* Have survived massive impacts in our time-line.
* Were diverse.

Branchiopoda (Usually fresh water shrimp): Asmussia - Image of generalized clam shrimp: http://www.fettes.com/orkney/Fossils/Images/Arthropod.jpg "This tiny branchiopod crustacean can be found in all Devonian sediments, and indicates a shallow water environment. It is common in the Upper Stromness and Rousay Flagstone group. Depending on the type of sediment and the conditions of fossilization Asmussia murchisoniana shows as a tiny (few mm) thin valve often with growth lines (concentric rings) visible. The crustacean belongs to the conchostracans or commonly called clam shrimps (the shrimp is housed between to chitin valves). Conchostracans occur on all continents and have a full range from the Palaeozoic up to recent time. They are filter feeders but also scrape and tear their food and scavenge on all organisms in their environment. They live in temporary pools or other shallow water conditions."
* Still can't tell if fresh water or salt water - possibility of both.
* Could they survive? Their relatives have survived extinction events up to present day.

Brachiopods (Appearance of bivalves, but not related): Atrypa - Information: http://www.palaeos.com/Invertebrates/Lophotrochozoa/Brachiopoda/Atrypidida.html Terebratula another example.
* Another group that has survived hardships, perhaps they will make it through this event also?

Bivalves: Aviculopecten - Image: http://upload.wikimedia.org/wikipedia/commons/4/4f/Aviculopecten_subcardiformis01.JPG Wilkingia another example.
* Little information on specific species
* Still confident bivalves in general will make it through.


Nautiloids:

Actinocerida: Example, Ormoceras - http://www.yale.edu/ypmip/taxon/ceph/38064sm.gif

Orthocerids: Geisonoceratidae - Squid-like orthocerids with long straight to slightly curved shells. Example: Michelinoceras Image: http://crnmac1.physics.uiowa.edu/fossils/Midwest_Cephalopods/IA_03/Michelinoceras_2.jpg Orthoceras Info: http://en.wikipedia.org/wiki/Orthoceras
* Likely scavengers to predators, could be wiped out.
* Thought to be quite diverse, perhaps some may scrape through?
Pseudorthoceratidae: A member of Orthoceratoidae. Very similar to orthocerids. http://en.wikipedia.org/wiki/Pseudorthoceratidae
* Survived up to 209.5 mya according to the article. Could they survive a meteorite impact?
* Possible predators. Maybe only the most opportunistic with the most varied diet could survive.

Ammonoids: Agoniatidia - Image: http://upload.wikimedia.org/wikipedia/commons/e/ef/Siphuncle.gif 409.1—360.7 mya
"Agoniatitida are primitive ammonoids with a ventral retrochoanitic siphuncle (septal necks point to the rear) reflective of their nautiloid ancestors.and goniatitic sutures with a variable number of lobes. Shells vary from discoidal to globular. Coiling may be loose with whorls barely touching or tight with a dorsal impression."
* Thought to have lived up until the extinction event, will they pass through?

Arthropods:

Eurypterids: Large predator. Low chance of survival.

Trilobites: One example,
Cyphaspis (little info available) Image: http://upload.wikimedia.org/wikipedia/commons/a/a1/CyphaspisPlate.jpg
* Information is sparse.
* Found in Late Devonian.

Scorpions: Example: Palaeophonus - http://en.wikipedia.org/wiki/Palaeophonus virtually identical to modern scorpions, a form too successful to be wiped out by a moderate meteorite. In for sure.

Springtails: Rhyniella praecursor - http://en.wikipedia.org/wiki/Rhyniella_praecursor http://www.abdn.ac.uk/rhynie/collembolan.htm
* Successful, has changed little over hundreds of millions of years. Enough to survive?
Looking good KayKay,I love the survivor list!
Oh boy! Mark soup!
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Ook
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kaykay leaved spec community ;)
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chillypaz2010
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Uh,oh... well,I guess there isn't any hope,or is there.
Edited by chillypaz2010, Oct 29 2010, 07:26 AM.
Oh boy! Mark soup!
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Dragon wasp
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i know it is very sad :(
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Forbiddenparadise64
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Well, I actually prefer the wipe out all chordates idea. I mean, all the non vertabrate chordate species today are specialised, and even if vertabrates perished, they'd never evolve into anything big, so they are probably more likely to die out than vertabrates. It is extremely unlikely a disease and an asteroid would kill off all vertabrates (unless it is GE). It would require a huge mass extinction to kill them off. Trilobites did survive quite along time, but most species perished in the Ordovician mass extinction, even more in the Devonian, and there were only 1 or 2 genuses by the Permian mass extinction, so I doubt they would survive especially to the present day. I presume if it was a mass extinction, it would wipe out Eurypterids, trilobites and perhaps over 50% of insects as well, and lots of other organims would die out. Groups like gastropods, cephalopods, echinoderms, brachipods, anthozoans(sea anemones and corals) and bryozoans, which have been hit very hard by past extinctions could be either wiped out completely or reduced to a really small number of relict species. Is this meant to start in the late Devonian? Than the Earth would have over 100 million years to recover before the Permian mass Extinction wiped out even more organisms. A world with an extinction big enough to wipe out all chordates in the Devonian would be biologically unrecognisable by the present day. Shame this project had to be abandoned. WHY? WHY? WHHHYYYY? JK, we could take command of it, though that would be unfair, or simply reinvent it.
Prepare for the Future Walking with the future: Allozoic (pts 4-6)http://s1.zetaboards.com/Conceptual_Evolution/topic/3252142/14/#new

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