0:07 well hi there this is a hagfish a
0:11 jawless slimy worm eating fish found in
0:13 the deep ocean and your nightmares and
0:16 you are basically the hagfish of
0:18 reptiles and I thought about ending this
0:20 right there but I guess I better explain
0:24 if you noticed I only called hagfish a
0:27 fish in quotes this is because it is
0:31 only arguably a fish at all heck it's
0:33 only arguably a vertebrate it is the
0:36 only vertebrate with a skull but no
0:39 actual vertebrae and it goes right here
0:42 on the vertebrate Tree of Life some of
0:44 you may be very familiar with these
0:47 diagrams but many of you probably are
0:50 not so I'd like to explain exactly how
0:52 these work this diagram called a
0:54 phylogeny depicts the proposed
0:56 relationships between different
0:58 organisms this tree shows the
1:00 relationship between different groups of
1:03 living vertebrates this tree shows the
1:06 relationships between three people Bob
1:09 Joe and Brian now as you may be able to
1:12 see Bob and Joe are more closely related
1:14 to one another than they are to Brian
1:16 this would be the case if for example
1:20 Bob and Joe are Brothers and Brian is
1:22 their cousin I would say that Bob and
1:24 Joe are more closely related because
1:27 while all three of them share ancestors
1:30 Bob and Joe share parents and not just
1:32 grandparents with one another because
1:35 they share more recent common ancestors
1:37 with one another than they do with Brian
1:40 they are more closely related even
1:41 though they do share ancestors with
1:45 Brian whichever two share ancestors more
1:47 recently with one another are more
1:49 closely related and the relationships
1:50 between them are the same if I draw the
1:54 phylogeny like this or like this or like
1:57 this and these branching points these
1:59 represent the last time that two
2:01 individuals or groups shared common
2:04 ancestors Brian shared all of these
2:07 ancestors with Bob and Joe
2:10 and this was the last time he shared
2:12 ancestors with either of them since he
2:15 shares the same ancestors with Bob and
2:18 Joe I can't say which one of them is
2:20 more closely related to Brian he is
2:22 equally related to both of them and that
2:24 isn't changed if I flip where I put Bob
2:28 and Joe on the phylogeny Bob however is
2:30 more closely related to Joe than he is
2:32 to Brian this is because he shares
2:34 ancestors more recently with Joe than he
2:37 does with Brian he shares ancestors with
2:39 both of them but he shares more reason
2:41 to ancestors with Joe and thus is more
2:44 closely related to Joe if I threw
2:46 Stewart onto the phylogeny as well and
2:49 saw that he goes here then I would be
2:51 able to see that Brian is more closely
2:54 related to Bob and Joe than he is to
2:56 Stuart I would also be able to see that
3:00 Stuart is equally related to Bob Joanne
3:01 Bryan because he shares the same
3:04 ancestors with all of them now I want to
3:07 note one final thing Bob and Joe with
3:09 their their parents form a family called
3:10 a clade
3:12 a clade also called a monophyletic group
3:15 is a common ancestor and all of its
3:19 descendants Brian Bob and Joe with their
3:21 most recent shared ancestors and
3:24 everyone in between also form a family a
3:27 clade and the same is true for Bob Joe
3:29 Bryan and Stuart with their most recent
3:31 shared ancestors and everyone in between
3:34 so it is possible to be part of multiple
3:38 families clades all at the same time and
3:40 no matter how many generations go by
3:42 their descendants will always be part of
3:45 those families as well that is why birds
3:47 can be dinosaurs reptiles tetrapods
3:49 vertebrates and animals all at the same
3:51 time and that doesn't mean that they
3:53 aren't unique or that they aren't Birds
3:56 even though Joe is in the same family as
3:58 Bob Brian and Stewart that doesn't
4:01 change the fact that Joe is unique from
4:04 Bob Brian and Stewart now let's say I
4:05 wanted to talk about a family a family
4:08 that includes both Bob and Brian I could
4:10 be talking about this family with
4:12 Stewart or this family without Stewart
4:14 which one is right
4:16 both of them so which one am I talking about
4:17 about
4:19 I might need to tell you and that brings
4:23 me to the hagfish here is a phylogeny of
4:25 the vertebrates or at least here is a
4:27 phylogeny that includes all of the
4:30 vertebrates now the question is do I
4:32 want to include the hagfish or do I not
4:35 that's up to me all of the other
4:36 vertebrates share more recent common
4:38 ancestors with all of the other
4:40 vertebrates than they do with the
4:43 hagfish I can include the hagfish and
4:44 the ancestors they share with the other
4:47 vertebrates or I cannot it's up to me
4:51 suppose now I am interested in the fish
4:54 what is a fish well I think it's fair to
4:57 say that trout are fish and sharks are
5:00 fish so I would need to look at the last
5:02 time that sharks and trout shared common
5:04 ancestors those would need to be fish as
5:07 well and everything that came from them
5:09 as I discussed in our video on whales
5:12 that group would include the whales so
5:14 while whales are mammals that doesn't
5:15 mean that they aren't part of the fish
5:18 family the fish clade as well if you
5:20 were interested in naming a clayed fish
5:22 they would have to be in it because
5:24 they're part of any family that includes
5:27 both sharks and trout but not the
5:29 hagfish they are part of some families
5:31 that include both sharks and trout but
5:33 unlike the whales they're not part of
5:35 every family that includes both sharks
5:37 and trout should they be part of my fish family
5:39 family
5:41 that's up to me and just one thing to
5:43 note here the lampreys are more closely
5:45 related to all of the other fish than
5:47 they are to the hagfish so I could even
5:50 include lampreys without including the hagfish
5:51 hagfish
5:54 poor hagfish are they just barely fish
5:56 or do they just miss the cut they don't
5:58 spend too long feeling bad for them
6:01 because you're in the same position here
6:04 are the reptiles or at least here is a
6:05 phylogeny that includes all of the
6:08 reptiles notice where the birds are
6:10 located I can't get them out of the
6:12 family without removing the crocodilians
6:14 and the turtles as well they're right in
6:16 the middle of the family I can't have a
6:19 reptile clade that includes snakes and
6:21 turtles without including the birds but
6:24 this clade that includes the lizards
6:26 Turtles birds and crocodilians called
6:30 the diopside clade does not include you
6:32 you aren't in it and yet everything
6:34 alive today that I would consider to be
6:37 a reptile is so clearly you are not a
6:39 reptile but what about this
6:40 or this
6:43 are these reptiles most would agree that
6:47 they probably are and yet these are part
6:49 of the family over here the synapse had
6:52 clayed and that Glade includes you too
6:54 you see you share more recent common
6:56 ancestors with a dimetrodon than
6:58 dimetrodon does with the rest of the
7:00 plastic reptiles in the bag of dinosaurs
7:04 or with any of the other diopsides so I
7:06 cannot create a clade that includes both
7:08 the metrodon and Gus Gus without
7:10 including you as well the synapses
7:13 including you can either be included or
7:16 excluded from this Glade because you are
7:18 basically the hagfish of reptiles and
7:20 now you know as always like And
7:21 subscribe and we hope to see you real soon
7:23 soon oh
7:24 oh
7:28 I'm so confused
7:30 so if I was in a call like create a
7:31 group called monkeys
7:34 I'd have to include the Apes including
7:35 us as well
7:37 so when people say you know you
7:38 shouldn't come from monkeys like no it's
7:41 worse I'm saying you are a monkey
7:45 okay that's if monkey is a thing so
7:48 if we just wanted to see stars in then
7:50 we're good we just have to add all the
7:51 new pterosomes all the anus first
7:52 developers all the people who speak out
