# Common ancestor of dog, crow and octopus? **URL:** \ **Category:** Factual Questions\ **Created:** [August 2, 2019, 8:24pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084 "2019-08-02T20:24:51Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![Walken\_After\_Midnight](https://avatars.discourse-cdn.com/v4/letter/w/b487fb/32.png) [@Walken\_After\_Midnight](https://boards.straightdope.com/u/Walken_After_Midnight)\ **Post date:** [August 2, 2019, 8:24pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/1 "2019-08-02T20:24:51Z")
I was having a bath and thinking about the intelligence of animals. In particular, I was thinking about how intelligence had evolved in diverse evolutionary lineages, such as dogs, crows and octopuses. Then I wondered what the common ancestor of the dog, crow and octopus was. So what is it? Also, what animals around today didn’t evolve from the common ancestor of the dog, crow and octopus? ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [August 2, 2019, 8:42pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/2 "2019-08-02T20:42:03Z")
I think the most restrictive clade including all three would be [Nephrozoa](https://en.wikipedia.org/wiki/Nephrozoa). I’m basing this on a very recent (like just now) degree in biology from the university of Wikipedia. Nephrozoa encompasses almost all animals, and the vast majority of those with bilateral symmetry. Bilateral exceptions appear to be [Xenacoelomorpha](https://en.wikipedia.org/wiki/Xenacoelomorpha) Non bilaterals include sponges, ctenophores, placozoans, and cnidarians. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [August 2, 2019, 8:46pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/3 "2019-08-02T20:46:05Z")
Dogs and crows are [deuterostomes](https://en.wikipedia.org/wiki/Deuterostome), while octopuses are [protostomes](https://en.wikipedia.org/wiki/Protostome). From that latter page: “The common ancestor of protostomes and deuterostomes was evidently a worm-like aquatic animal. The two clades diverged about 600 million years ago.” ---
**Author:** ![Triskadecamus](https://avatars.discourse-cdn.com/v4/letter/t/b19c9b/32.png) [@Triskadecamus](https://boards.straightdope.com/u/Triskadecamus)\ **Post date:** [August 2, 2019, 8:52pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/4 "2019-08-02T20:52:54Z")
Dogs and crows are very much more closely related than Octopuses. Both dogs and crows are vertebrates, while octopuses are mollusks. There are dozens of iterations of the “tree of life” over the last decade alone. Some stem species which produced mollusks would be the likely source for all the vertebrates. Jellyfish would probably not be descendants of that species. Maybe sponges, but I am not sure about that. Tris ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [August 2, 2019, 9:14pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/5 "2019-08-02T21:14:51Z")
Here’s a pretty good (and up to date, I think) tree of life diagram that allows you to drill down. > **[Animal | Phylogeny](https://en.wikipedia.org/wiki/Animal#Phylogeny)** > > Animals are monophyletic, meaning they are derived from a common ancestor. Animals are sister to the Choanoflagellata, with which they form the Choanozoa. The most basal animals, the Porifera, Ctenophora, Cnidaria, and Placozoa, have body plans that lack bilateral symmetry. Their relationships are still disputed; the sister group to all other animals could be the Porifera or the Ctenophora, both of which lack hox genes, important in body plan development. > These genes are found in the Placozoa an... You will find dog & crow under \Nephrozoa\Deuterostomia\Chordata You will find the octopus under \Nephrozoa\Protostomia.…\Mollusca The MRCA of dog, crow & octopus is (I think) the ancestor of all animals with any kind of central nervous system. Neurons evolved earlier than this, however. The outgroups Cnidaria and Ctenophora have a decentralized nervous system. Porifera do not. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [August 2, 2019, 9:17pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/6 "2019-08-02T21:17:22Z")
This has more: > **[Cephalization](https://en.wikipedia.org/wiki/Cephalization)** > > Cephalization is an evolutionary trend in which, over many generations, the mouth, sense organs, and nerve ganglia become concentrated at the front end of an animal, producing a head region. This is associated with movement and bilateral symmetry, such that the animal has a definite head end. This led to the formation of a highly sophisticated brain in three groups of animals, namely the arthropods, cephalopod molluscs, and vertebrates. > Cnidaria, such as the radially symmetrical Hydrozoa, show s... ---
**Author:** ![Walken\_After\_Midnight](https://avatars.discourse-cdn.com/v4/letter/w/b487fb/32.png) [@Walken\_After\_Midnight](https://boards.straightdope.com/u/Walken_After_Midnight)\ **Post date:** [August 2, 2019, 9:25pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/7 "2019-08-02T21:25:23Z")
Thanks for the replies. So, “a worm-like aquatic animal” looks to be the common ancestor of the dog, crow and octopus then. I suspected it might be something like a jellyfish for the living non-dog/crow/octopus ancestor. > [@naita](#): > > sponges, ctenophores, placozoans, and cnidarians These names made me think of the alien species [in Star Trek](https://en.wikipedia.org/wiki/Tribble). 😃 > [@scr4](#): > > Dogs and crows are [deuterostomes](https://en.wikipedia.org/wiki/Deuterostome), while octopuses are [protostomes](https://en.wikipedia.org/wiki/Protostome). From the first article: > [@](#): > > in deuterostomes, the first opening (the blastopore) becomes the anus, while in protostomes, it becomes the mouth. ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [August 2, 2019, 9:36pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/8 "2019-08-02T21:36:48Z")
> [@Walken\_After\_Midnight](#): > > Then I wondered what the common ancestor of the dog, crow and octopus was. The common ancestor of dogs and crows is going to be some kind of dinosaur. Birds came from dinosaurs. Mammals came from therapsids which came from dinosaurs. Molluscs are a whole other ballgame. They are protostomes, so you’ll have to go way back to find that common ancestor. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [August 2, 2019, 9:38pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/9 "2019-08-02T21:38:43Z")
> [@Walken\_After\_Midnight](#): > > So, “a worm-like aquatic animal” looks to be the common ancestor of the dog, crow and octopus then. I suspected it might be something like a jellyfish for the living non-dog/crow/octopus ancestor. No, a jellyfish is not a bilaterian. It’s in the phylum [cnidaria](https://en.wikipedia.org/wiki/Cnidaria). The last common ancestor between the dog, crow and octopus is still a bilaterian. I think the [urbilaterian](https://en.wikipedia.org/wiki/Urbilaterian) is how it’s referred to as. ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [August 2, 2019, 9:54pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/10 "2019-08-02T21:54:34Z")
> [@HMS\_Irruncible](#): > > The common ancestor of dogs and crows is going to be some kind of dinosaur. Birds came from dinosaurs. Mammals came from therapsids which came from dinosaurs. Incorrect. Synapsids (including Therapsids and mammals) and reptiles (including dinosaurs and birds) split about 100 million years before the dinosaurs appeared; mammals themselves predate the dinosaurs. In fact, nether is descended from the other - they both evolved from the basal amniotes, which were the first vertebrates that could lay eggs on land. ---
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [August 3, 2019, 5:06am UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/11 "2019-08-03T05:06:02Z")
This is a cool visualization: [http://lifemap-ncbi.univ-lyon1.fr/](http://lifemap-ncbi.univ-lyon1.fr/) In the lower left, where it says “imput[sic] multiple taxid”, type this in and click “view”: ```auto 28725 6643 9608 ``` (That’s just the codes for octopus, corvids, and canines). ---
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [August 3, 2019, 5:15am UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/12 "2019-08-03T05:15:41Z")
There’s also this text-based tool using a similar dataset: [https://www.ncbi.nlm.nih.gov/Taxonomy/CommonTree/wwwcmt.cgi](https://www.ncbi.nlm.nih.gov/Taxonomy/CommonTree/wwwcmt.cgi) It returns this: ```auto Metazoa +-Chordata | ++Aves | | \-Corvus | \+Mammalia | \-Canidae \-Mollusca \-Cephalopoda \-Octopoda \-Octopodidae \-Octopus ----------------------------------- ``` Or phylogenetically: ```auto Bilateria +-Deuterostomia | \-Chordata | \-Craniata | \-Vertebrata | \-Gnathostomata | \-Teleostomi | \-Euteleostomi | \-Sarcopterygii | \-Dipnotetrapodomorpha | \-Tetrapoda | \-Amniota | ++Sauropsida | | \-Corvus | \+Mammalia | \-Canidae \-Protostomia \-Lophotrochozoa \-Mollusca \-Cephalopoda \-Coleoidea \-Neocoleoidea \-Octopodiformes \-Octopoda \-Incirrata \-Octopodidae \-Octopus ----------------------------------- ``` But none of these are as exciting as “worm-like aquatic animal” 😉 ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [August 3, 2019, 9:12pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/13 "2019-08-03T21:12:56Z")
> [@Alessan](#): > > Incorrect. > > Synapsids (including Therapsids and mammals) and reptiles (including dinosaurs and birds) split about 100 million years before the dinosaurs appeared; mammals themselves predate the dinosaurs. In fact, nether is descended from the other - they both evolved from the basal amniotes, which were the first vertebrates that could lay eggs on land. So is there any suggestion what the common ancestor would have looked like? (Maybe something more exciting than aquatic worm-like animal? He said hopefully ) ---
**Author:** ![Kamino\_Neko](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kamino_neko/32/34_2.png) [@Kamino\_Neko](https://boards.straightdope.com/u/Kamino_Neko)\ **Post date:** [August 3, 2019, 9:24pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/14 "2019-08-03T21:24:47Z")
> [@Northern\_Piper](#): > > So is there any suggestion what the common ancestor would have looked like? (Maybe something more exciting than aquatic worm-like animal? He said hopefully ) The first amniote (the group including the synapsids and reptiles) was probably small lizard-like thing called Casineria. [Wiki for Casinaria.](https://en.wikipedia.org/wiki/Casineria) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 3, 2019, 10:35pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/15 "2019-08-03T22:35:17Z")
And the worm-like animal was probably similar to a planarian. Superficially, at least-- modern planaria are just as highly evolved as any other creature on the planet, and have probably developed all sorts of differences “under the hood”. ---
**Author:** ![Mr.Bill](https://avatars.discourse-cdn.com/v4/letter/m/5f9b8f/32.png) [@Mr.Bill](https://boards.straightdope.com/u/Mr.Bill)\ **Post date:** [August 4, 2019, 3:01am UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/16 "2019-08-04T03:01:59Z")
The book **Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness** by Peter Godfrey-Smith is well worth a read. The author spends some time talking about exactly your question. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [August 4, 2019, 2:24pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/17 "2019-08-04T14:24:22Z")
> [@Northern\_Piper](#): > > So is there any suggestion what the common ancestor would have looked like? (Maybe something more exciting than aquatic worm-like animal? He said hopefully ) > [@Chronos](#): > > And the worm-like animal was probably similar to a planarian. Superficially, at least-- modern planaria are just as highly evolved as any other creature on the planet, and have probably developed all sorts of differences “under the hood”. It would probably be something like the previously mentioned [Xenocoelomorpha](https://en.wikipedia.org/wiki/Xenacoelomorpha), including “flatworms” like [Xenoturbella.](https://en.wikipedia.org/wiki/Xenoturbella) They are bilaterally symmetric, but have a simple digestive system with a single opening that serves as both mouth and anus. They are regarded as the “sister group” to the group that includes the ancestors of both vertebrates and mollusks, so the common ancestor of all these groups most likely looked something like this. (The distant common ancestor of most animals above sponges and jellyfish is going to be some kind of “aquatic worm-like animal.”) As mentioned, mollusks and vertebrates differ fundamentally in their early embryology in the way the digestive system acquires a second opening. In mollusks, the first opening becomes the mouth, and the anus forms later. In vertebrates, the anus is the first opening, and the mouth forms second. ---
**Author:** ![Trancephalic](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/trancephalic/32/380_2.png) [@Trancephalic](https://boards.straightdope.com/u/Trancephalic)\ **Post date:** [August 4, 2019, 4:36pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/18 "2019-08-04T16:36:12Z")
Everyone’s just an asshole when they’re young. ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [August 4, 2019, 8:45pm UTC](https://boards.straightdope.com/t/common-ancestor-of-dog-crow-and-octopus/838084/19 "2019-08-04T20:45:40Z")
Or a big mouth, apparently.