Mysticete
Well-known member
I thought about making this part of making this a part of an existing thread, and it has certainly come up several times. But I think its a distinct enough idea to deserve its own thread, even if a whopping four people care about this stuff here (lolz?)
I am a taxonomy nerd. Before I was even a birder I was making lists of critters. One of my current projects is to create my own checklist, the subspecies groups project an outgrowth of that, as are my posts. I am also a paleontologist by training. Those two things make me incredibly interested in the concept of using time-calibration to create an intrinsically less random and arbitrary system of classification. At present, other than marking the existence of a clade, whether something is a family or a order or a subfamily doesn't actually mean anything. But what if it could? What if you COULD fix the age of families to a set time period, and directly correlate them to events in geologic history? A large number of zoom meetings this week and....well...boredom during them, has made me explore this concept in more detail.
This is not an original idea. Avise a long-time ago argued for this to be considered for all life, and the Avitaxonomicon (a great reference site!) previously has made a big push. My big complaint with the latter is that the dates the author chose are arbitrary. But what if you could pick major periods of climate and geologic change, which might be expected to influence diversification rates. I already apply this to orders in my own taxonomy, using the Paleocene-Eocene Thermal Maximum as the cut-off age for orders of birds, as it is well known to be a major period of diversification for mammals and birds (and works with very little modification of the existing taxonomy). Could other events be just as useful, and how might it change ranks?
Caveats of course: Many bird groups lack any sort of time-calibrated phylogeny, and methods, choice of sampled taxon, and calibration points can also mess things up.
At any rate, to start off I decided to test the most conservative cut off for Families: For a Family to exist it had to have been present in the Eocene or earlier, or close enough. A hard cut off would automatically demote ANY FAMILY that was younger, while a soft cut off would allow younger families but elevate anything present in the Eocene to family level if not already recognized. The Eocene was a time of warm tropical temperatures that started in the PETM (the warmest period in Earth History since the extinction of the dinosaurs, with some gradual cooling towards the end. It was a major period of diversification for life, with tropical rainforests above the Arctic circle and vasts circumpolar forests that allowed free interchange of critters. Personally this would not be my preferred cut off point since I would prefer one that marked a more significant global change from my cut-off point for Orders.
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In the next post I will show my results for the Eocene
I am a taxonomy nerd. Before I was even a birder I was making lists of critters. One of my current projects is to create my own checklist, the subspecies groups project an outgrowth of that, as are my posts. I am also a paleontologist by training. Those two things make me incredibly interested in the concept of using time-calibration to create an intrinsically less random and arbitrary system of classification. At present, other than marking the existence of a clade, whether something is a family or a order or a subfamily doesn't actually mean anything. But what if it could? What if you COULD fix the age of families to a set time period, and directly correlate them to events in geologic history? A large number of zoom meetings this week and....well...boredom during them, has made me explore this concept in more detail.
This is not an original idea. Avise a long-time ago argued for this to be considered for all life, and the Avitaxonomicon (a great reference site!) previously has made a big push. My big complaint with the latter is that the dates the author chose are arbitrary. But what if you could pick major periods of climate and geologic change, which might be expected to influence diversification rates. I already apply this to orders in my own taxonomy, using the Paleocene-Eocene Thermal Maximum as the cut-off age for orders of birds, as it is well known to be a major period of diversification for mammals and birds (and works with very little modification of the existing taxonomy). Could other events be just as useful, and how might it change ranks?
Caveats of course: Many bird groups lack any sort of time-calibrated phylogeny, and methods, choice of sampled taxon, and calibration points can also mess things up.
At any rate, to start off I decided to test the most conservative cut off for Families: For a Family to exist it had to have been present in the Eocene or earlier, or close enough. A hard cut off would automatically demote ANY FAMILY that was younger, while a soft cut off would allow younger families but elevate anything present in the Eocene to family level if not already recognized. The Eocene was a time of warm tropical temperatures that started in the PETM (the warmest period in Earth History since the extinction of the dinosaurs, with some gradual cooling towards the end. It was a major period of diversification for life, with tropical rainforests above the Arctic circle and vasts circumpolar forests that allowed free interchange of critters. Personally this would not be my preferred cut off point since I would prefer one that marked a more significant global change from my cut-off point for Orders.
.
In the next post I will show my results for the Eocene
