Saturday, May 2, 2020

Rudists, Nudists, and Buddhists

     Although we have already discussed rudist (not rudest) clams here at PEOTS, new research about these reef builders of the Cretaceous was just published in February, 2020, warranting another look. Plus, I like the "Rudists, Nudists, and Buddhists" title. Rudists colonizing in zen-like seas? Count us in. 



        The earth turned faster at the end of the Cretaceous than it does today, rotating 372 times a year, compared to the current 365 1/4, according to a new study of fossil rudist shells. The research also shows a day lasted only 23.5 hours, according to the new study in American Geophysical Union's journal Paleoceanography and Paleoclimatology.




     The ancient mollusk, from an extinct and quite diverse group known as rudist clams, grew fast, laying down daily growth rings. The new study used lasers to sample minute slices of shell and count the growth rings with great accuracy. The growth rings allowed the researchers to determine the number of days in a year and more accurately calculate the length of a day 70 million years ago. The new measurement informs models of how the Moon formed and how close to Earth it has been over the 4.5-billion-year history of the Earth-Moon gravitational dance.



     The high resolution obtained in the new study combined with the fast growth rate of the ancient bivalves revealed unprecedented detail about how the animal lived and the water conditions it grew in, down to a fraction of a day.
     "We have about four to five datapoints per day, and this is something that you almost never get in geological history. We can basically look at a day 70 million years ago. It's pretty amazing," said Dr.  Niels de Winter, an analytical geochemist at Vrije Universiteit Brussel and the lead author of the new study.


     Climate reconstructions of the deep past typically describe long term changes that occur on the scale of tens of thousands of years. Studies like this one give a glimpse of change on the timescale of living things and have the potential to bridge the gap between climate and weather models.
     Chemical analysis of the shell indicates ocean temperatures were warmer in the Late Cretaceous than previously appreciated, reaching 40 degrees Celsius (104 degrees Fahrenheit) in summer and exceeding 30 degrees Celsius (86 degrees Fahrenheit) in winter. The summer high temperatures likely approached the physiological limits for mollusks, de Winter said.


     "The high fidelity of this data-set has allowed the authors to draw two particularly interesting inferences that help to sharpen our understanding of both Cretaceous astrochronology and rudist palaeobiology," said Dr. Peter Skelton, a retired paleobiologist at the Open University and a rudist expert unaffiliated with the new study.
    The new study analyzed a single individual that lived for over nine years in a shallow seabed in the tropics -- a location which is now, 70-million-years later, dry land in the mountains of Oman.
     "Torreites sanchezi mollusks look like tall pint glasses with lids shaped like bear claw pastries. The ancient mollusks had two shells, or valves, that met in a hinge, like asymmetrical clams, and grew in dense reefs, like modern oysters. They thrived in water several degrees warmer worldwide than modern oceans."
     In the late Cretaceous, rudists like T. sanchezi dominated the reef-building niche in tropical waters around the world, filling the role held by corals today. They disappeared in the same event that killed the non-avian dinosaurs 66 million years ago.


     "Rudists are quite special bivalves. There's nothing like them living today," de Winter said. "In the late Cretaceous especially, most of the reef builders are these bivalves. So they really took on the ecosystem building role that the corals have today."
     The new method focused a laser on small bits of shell, making holes 10 micrometers in diameter, or about as wide as a red blood cell. Trace elements in these tiny samples reveal information about the temperature and chemistry of the water at the time the shell formed. The analysis provided accurate measurements of the width and number of daily growth rings as well as seasonal patterns. The researchers used seasonal variations in the fossilized shell to identify years.


     The new study found the composition of the shell changed more over the course of a day than over seasons, or with the cycles of ocean tides. The fine-scale resolution of the daily layers shows the shell grew much faster during the day than at night.
     "This bivalve had a very strong dependence on this daily cycle, which suggests that it had photosymbionts," de Winter said. "You have the day-night rhythm of the light being recorded in the shell."



     This result suggests daylight was more important to the lifestyle of the ancient mollusk than might be expected if it fed itself primarily by filtering food from the water, like modern day clams and oysters, according to the authors. De Winter said the mollusks likely had a relationship with an indwelling symbiotic species that fed on sunlight, similar to living giant clams, which harbor symbiotic algae.
     "Until now, all published arguments for photosymbiosis in rudists have been essentially speculative, based on merely suggestive morphological traits, and in some cases were demonstrably erroneous. This paper is the first to provide convincing evidence in favor of the hypothesis," Skelton said, but cautioned that the new study's conclusion was specific to Torreites and could not be generalized to other rudists.


     De Winter's careful count of the number of daily layers found 372 for each yearly interval. This was not a surprise, because scientists know days were shorter in the past. The result is, however, the most accurate now available for the late Cretaceous, and has a surprising application to modeling the evolution of the earth-moon system.
     The length of a year has been constant over earth's history, because earth's orbit around the sun does not change. But the number of days within a year has been shortening over time because days have been growing longer. The length of a day has been growing steadily longer as friction from ocean tides, caused by the moon's gravity, slows earth's rotation.



    The pull of the tides accelerates the moon a little in its orbit, so as earth spin slows, the moon moves farther away. The moon is pulling away from earth at 3.82 centimeters (1.5 inches) per year. Precise laser measurements of distance to the moon from earth have demonstrated this increasing distance since the Apollo space program left helpful reflectors on the moon's surface.
     But scientists conclude the moon could not have been receding at this rate throughout its history, because projecting its progress linearly back in time would put the moon inside the earth only 1.4 billion years ago. Scientists know from other evidence that the Moon has been with us much longer, most likely coalescing in the wake of a massive collision early in Earth's history, over 4.5 billion years ago. So the Moon's rate of retreat has changed over time, and information from the past, like a year in the life of an ancient clam, helps researchers reconstruct that history and model of the formation of the moon.

       Rudists' growth patterns and rates provide great data for models from the Cretaceous.

Have you encountered any rudists in your fossil meanderings around the earth?
Steph

121 comments:

  1. I thought of writing the research date as February 2020, "B.C." (Before Covid-19 spike in the U.S.) but decided it's refreshing to read an article not mentioning the novel coronavirus.

    Also refreshing? First thunderstorms of the year this evening. . .

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  2. Sorry, I missed the connection to nudists and Buddhists. Or was that just PEOTS clickbait?

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    1. "Rudists colonizing [like nudists] in zen-like [like Buddhists] seas? Count us in."

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    2. I try to avoid clickbait in any form.

      Now I am wondering why it is called a nudist colony (not a group or a bunch or a gathering). Do nudists work together like ants? Or do they quarantine as in leper colonies? Are they being original like the 13 original colonies?

      So many questions (but not during a Buddhist retreat).

      I did rediscover this gem today:

      "Sometimes I sit and think; sometimes I just sit."

      --A. A. Milne--

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    3. Apparently, they're not called colonies anymore. Per Wikipedia, "Nudist colony is no longer a favored term, but it is used by naturists as a term of derision for landed clubs that have rigid non-inclusive membership criteria."

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    4. More jargon. "Landed clubs" -- hmmmmm.

      I think I'll go in my backyard and watch the hills of ant resorts.

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    5. They're probably not wearing clothes, either, you voyeur!

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    6. . . .And, the day this post was published was on World Naked Gardening Day!. Mark your calendars for the first Saturday in May.

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  3. I've mentioned sleeping during "Wait, Wait, Don't Tell Me" several times a week. But I'm always awake during the intro of the first caller. What are the odds that two weeks in a row, it's a female rocket scientist? Last week we had Elena from Pasadena, CA, who works on the Curiosity rover at NASA's Jet Propulsion Lab. This week, it's Anna from Golden, CO, an electrical test engineer for the Orion spacecraft. Weird.

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    Replies
    1. I noticed that, too.

      Do you want to do the math?

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    2. No, I'll leave it to them...

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  4. jan and others who regularly frequent PEOTS:
    You ought to all be awarded an advanced degree in geology (and probably also linguistics!). When Word Woman invites us into her "classroom" we all become smarter... in the most interesting and entertaining way imaginable. She makes learning fun!
    Also interestingly, somewhere in the comment above (in which Word Woman closes with the A.A. Milne quotation) there is an unintentional yet clairvoyant allusion to the answer to the "Schpuzzle of the Week" that will appear in the May 8 edition of Puzzleria!, which celebrates its sixth anniversary this Friday.
    Incidentally, Word Woman (who launched her Partial Ellipsis Of The Sun blog October 2013) was very generous with her time and expertise in helping me launch my puzzle blog, walking me, a Luddite, through the Blogger process. My heartfelt thanks to her.

    LegoThePooh

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    Replies
    1. Wow, Lego, congrats on 6 years of Puzzleria! We'll wander over for the unintentional cross-pollination of blog ideas. Something in the air perhaps (pollen?)?

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    2. Pollin! So that's what this song was about.

      LegoWhoAdmitsThatPollinIsProbablyBetterThan...Well,YouKnow

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    3. Lego, are you polling for pollen? Pulling for pollen?

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  5. Replies
    1. Great link, Word Woman. Those Jupiter images are breathtaking.
      All I know is, if the Earth were as massive as Jupiter, social distancing would be much easier!

      LegoJenniferJupiter

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    2. Lego, it's a gas.

      Juniper and gin?

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  6. If you're looking for a new time killer, SpaceX has posted an ISS docking simulator. Easier than an lunar landing simulator, it starts you off about 200 m from the ISS, not well aligned with the docking module, and in a poor but stable attitude (like so many of us). The goal is to dock VERY gently.

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  7. Replies
    1. They should play "The Blue Danube" in the background.

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    2. Their database of ISS components is incredibly complete. I flew a square loop over and around the ISS (from 100 m away, translate up 100 m, pitch down 90 deg, translate up 200 m, pitch down 90 deg, rinse and repeat, etc), and was amazed by the detail visible in each module.

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    3. ... Of course, they're planning to fly a couple of guys up there for real on Wednesday, so one would hope they've got a good set of plans.

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    4. I'm disappointed that the simulator lets me dock only with the International Docking Adapter at the forward end of the Harmony node, but not with the IDA at the zenith.

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    5. Found an Easter Egg: From your initial position, turn around (yaw 180 degrees away from the ISS), and you find yourself about 20 meters from a red Tesla Roadster. It apparently disappears if you try to get behind it, and if you crash into it, you're told that you crashed into the ISS.

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  8. Replies
    1. Thanks!

      Glacier moss balls vs. glacier moth balls?

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    2. I think I just read the glacier mice article and missed the sabre-toothed anchovies, first time around.

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  9. "Height modernization": I've gotta teach my doctor that term the next time she tries to tell me I'm not as tall as I was in college!

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  10. If you replace all the sheepherders in New Zealand with robot dogs, you really don't need all that many people in New Zealand. And without all those people (and their dogs) eating mutton, you really don't need all that many sheep. And if only they didn't look so much like the dogs in "Metalhead"... nah, it's still be pretty dystopian....

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  11. Replies
    1. Have you been able to view any of the maps? Every time I try to load one, I get an "Internal System Error" message.

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    2. I get that message, too. I sent them a notice of the error.

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  12. Replies
    1. The author blogs and podcasts as Grammar Girl, which sounds like a Word Woman sidekick in a comic book universe. "Mignon" is a name that sounds much nicer than it looks. Its a shame to discuss typefaces without mentioning dingbats (particularly, my favorite printing term, Zapf Dingbats), or the Comic Sans controversy.

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    2. My daughter absolutely hates Comic Sans.

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    3. Weird to have mentioned Mignon just a few days before Matt Mignone of Bethpage gets The Call.

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    4. I thought so, too. Bethpage just rolls off the tongue, eh?

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    5. It was named after the Biblical town Bethphage, which was between Jericho and Jerusalem, from which Jesus sent his disciples to find a colt, upon which he would ride into Jerusalem. Bethpage, NY, is on Long Island, between Jericho, NY, and Jerusalem Avenue in Massapequa, where I grew up.

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    6. Wow, fascinating. You are better than Google!

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    7. I'm a real font of information....

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    8. I like Cooper Black and all that nestling. . .

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  13. Replies
    1. I cited sabre-toothed anchovies above.

      On my usual weekend ride down the Southwest Corridor Park bikeway and beyond, I noticed that the Franklin Park Zoo was open for the first time in 3 months, so we took the granddaughters on a field trip from Home Vacation (the 3-year old's term for the pandemic quarantine) this morning. Had a great time, good social distancing and mask-wearing behavior on the part of the visitors, and good supportive modifications by the zoo staff, including lots of very liquidy hand sanitizer stations supplied by a local distillery.

      Both kids especially liked the prairie dog (which the 3-yo called "fairy dogs") exhibit in the children's section. My wife cautioned me not to point out the explanatory material that described prairie dogs as the almost exclusive diet of the endangered black-footed ferret. My reaction was, hell, of course they're endangered; if your entire diet consists of a single species, you've got to expect serious supply chain issues. I mean, a killer asteroid is one thing, but if your whole existence depends on a single, admittedly cute, rodent, extinction shouldn't come as a big surprise.

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    2. Ah, so.

      Glad you all had fun with the prairie/fairy dogs, despite the supply chain issue.

      Our zoo just opened up, too.

      Wish I were at the Cape, though, hanging with family, friends, and puzzlers all!

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    3. I saw (and smelled) one blooming at the Denver Botanic Gardens a few years ago.

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  14. Replies
    1. Could be. How conventional to have a convention of unconventional folks.

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  15. Replies
    1. Browsing the map brings back memories of our trip 6 (!) years ago.

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    2. Cool that you can see all this even without specialized GIS software!

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  16. You just need to know a couple basic Greek roots to know what an endorheic basin is, without needing to read the cartoon. What I want to know is, how come geologists don't double the "r", to get "endorrheic", like medics do? We have to remember not just the silent "h" but also the stupid double "r" in seborrhea, diarrhea, hemorrhage, hemorrhoids, etc. Such a bloody pain in the ass, if you ask me! Why do geologists with rocks in their heads get off easy?

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    Replies
    1. Endorrheic is an alternate spelling. . .

      It is odd, though. Rrocks in our heads are not part of the answer.

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  17. Speaking of colonies: Are you a fan of these diatom colonies?

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  18. Replies
    1. It's been cloudy here recently; I haven't had a chance to see it yet. I remember Hale-Bopp fondly.

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    2. We saw it here early one morning. My cellphone camera capability didn't do it justice, though.

      Hale-Bopp was awesome from Snow Mountain Ranch near Frasier, CO.

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  19. Replies
    1. What a strange thing to spend much time on...

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  20. Replies
    1. Those illustrations are gorgeous.

      Maizie is hanging in there. Taking it day by day, walk by walk. Thanks for asking.

      Delete
  21. Fire tornado! Cool! Maybe if we keep up our climate assault, we could get us a Great Red Spot like Jupiter!

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    Replies
    1. We Californians are a special breed. Our next trick will be acid rain hurricanes.

      2020 hindsight will not be so good.

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  22. Replies
    1. Yes, I read this article over the weekend. Our planet is in trouble, big trouble (not good trouble).

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  23. More planet trouble. Colorado wildfires, record heat in Death Valley...

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    1. My brother-in-law and his wife have been quarantining in their Vail, CO, condo. He's not too concerned by the wildfires, since he says they'd be evacuated to a 5-star hotel.

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    2. I hope they are okay. The smoke here in Denver has been quite thick. Pretty sunrises and sunsets but not so great for breathing.

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    3. We've had fairly heavy smoke for the past few days, not as bad as 3 years ago, or even 2 years ago (but it's still Preseason). "Airnow.gov" has had us in the Unhealthy status of late.

      The big bummer is most of us don't have air conditioning, we rely on open windows and gentle breezes for cooling. But in this little heat wave we've been balancing stuffy and hot indoor air vs cooler and smoky outdoors, not good for sleep.

      But my car has a lovely ashen sheen.

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    4. Hi, eco. Good to see you here. I am alternating turning the swamp cooler on and off to mitigate the smoke smell but stay somewhat cool.

      Friends from Vacaville, CA, have evacuated.

      Stay safe out there. Hope the breathing gets easier in both CA and CO.

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  24. From Karen Chee, via Twitter:

    When someone older pauses while speaking I think, ah yes, you’re putting two spaces after each period

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  25. NASA says an asteroid is headed our way right before Election Day.

    "When outer space sends its pebbles, they're not sending their best. ... They're sending pebbles that have lots of problems, and they're bringing those problems with us. They're bringing iron. They're bringing chondrites. They're pyrimidine and polycyclic aromatic hydrocarbons. And some, I assume, are good pebbles,"

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  26. I'm pretty sure I posted about this already, but I can't find the evidence now. Anyway, even if it hits (0.41% chance), the estimated energy is only 0.4 kt (less than a tenth of the Beirut blast). It's astronomically unlikely to hit anywhere useful, like the White House.

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    1. Agreed (about the impact, not about whether you posted this). I'm surprised they call it an asteroid, though maybe it fits the technical definition. I prefer pebble.

      And even on the small chance most will probably burn/ disintegrate when exposed to the open atmosphere, just like that similar size rock in the White House.

      When I was a kid a neighbor and I used to do a lot of sky observing; one night we had the very good fortune of seeing a fireball almost directly above - couldn't tell its size, but we could distinctly see the shape of the rock within the surrounding flame. It seemed to be moving relatively slowly - compared to typical flashes of dust as shooting stars, and it flew clear to the horizon.

      No pictures, but a cool mental imprint.

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    2. eco, seeing the shape of the hurtling rock sounds quite awesome.

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  27. Replies
    1. I'm so disappointed that the original paper uses the term "Venusian life". To quote Neil deGrasse Tyson, "The proper word for someone from Venus, -- the planet of love, beauty, and its consequences — is “Venereal.” But medical doctors took the word before astrophysicists did. So we’re stuck with “Venusians”.

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    2. I like Venusians.

      “It’s time to prioritize Venus.”

      And, of course, Randall Munroe is on it!

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    3. God must think like a political spin doctor. You know how they always release embarrassing information on Friday evening, to avoid heavy press coverage? Well, if you were going to arrange for the discovery of extraterrestrial life, which basically throws the Book of Genesis out the window, when would you do it? Why, in 2020, of course, in the middle of a pandemic, recession, social unrest, a presidential election campaign, wildfires, hurricanes, etc., etc., of course!

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  28. Replies
    1. Aw, thanks jan. Maizie and I loved a good road trip, especially to the Great Sand Dunes. I am sure she is digging in the sand somewhere and smelling good smells.

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    2. Did Maizie depart? So sorry to hear that. If only a dog's compassion could run as long as it does deep.

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    3. Sadly, yes. She was an amazing and beloved dog. I miss her so very much. Thanks for your condolences, eco.

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    4. Maizie at San Luis Park southwest of the Great Sand Dunes. Some very fine and sandy memories

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    5. A new post about Maizie May is now up.

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  29. Eco, I accidently deleted your post. Sorry. I am glad to see you back here at PEOTS!

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    Replies
    1. No worries, just wanted to make sure everyone was up on the news.

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