Drunk on Geomorphology - Dead Horse Amber Ale

 

The next Drunk on Geology is for Dead Horse Amber Ale from the Moab Brewery in Moab, Utah. 

The first thing that sticks out about the beer is easily the name "Dead Horse", and although it is a grisly name, it is actually named after a geological feature nearby to the brewery, Dead Horse Point State Park, which is located outside of Moab near Canyonland National Park. The name of the park comes from a legend where cowboys would fence off wild mustang horses along the overlook, taking what horses they wanted and leaving the horses they didn't penned up to die of thirst. 

Above is an image taken from the overlook at Dead Horse Point State Park looking off towards the southeast. The river there is the Colorado River far below. Between us and the river lies 100 million years of geological history. From top (youngest) to bottom (oldest) the rock units go like this:

Entrada Formation: Jurassic (150 million years old) - This is a sandstone formed from a coastal dune environment. These are what the arches at Arches National Park are found in.

Navajo Sandstone: Jurassic (175 million years old) - Wind deposited, prehistoric "petrified" sand dunes from an ancient erg (sand sea), colored a light tan or white color. The units also preserve phenomenal cross bedding features from the sand dunes. These rocks form the majority of the rock formations in Zion National Park.

Kayenta Formation: Late Triassic (180 million years old) - A series of sandstones, shales, and limestones from a meandering river environment that frequently preserves dinosaur tracks. This formation is very well observed in the nearby Canyonlands National Park.

Wingate Sandstone: Triassic (200 million years old) - Like the Navajo, another wind deposited preserved series of sand dunes, however usually with more of a red tint to the rocks (rust). 

Chinle Formation: Triassic (210 million years old) - A stream deposited series of mudstone, sandstone, and conglomerates. Well known for containing uranium deposits, petrified wood, and fossils. You can see some of the ancient uranium mines in nearby Capitol Reef National Park.

Moenkopi Formation: Early Triassic (230 million years old) - A tidal flat deposited series of brown to red mudstones. The rocks will often feature ripple marks and raindrop imprints. You can see this formation especially well along the western entrance to Capitol Reef National Park.

Cutler Formation: Permian (250 million years old) - Comprised of sandstone and conglomerate, this formation was deposited along a coastal-marine beach with off-shore sands and non-marine alluvial floodplain deposits intermixed. The most notable feature of the Cutler is the White Rim Sandstone.

Honaker Trail Formation: Pennsylvanian to Permian (286-320) - Down at the level of the river lies this shallow sea deposit comprised of dark grey limestones with fossils. 

You'll note on the can though that is says "10 million years in the making" which is clearly not a reference to any of the rocks which are far older than 10 million years old. This is actually a reference to the location that this point is on, which is the Colorado Plateau. This region of the country has slowly been uplifted over the past 10 million years and the Colorado River at this overlook is a prime example of the effect of that uplift. 

Text on the side of the can:

"Dead Horse Ale is named after the scenic overlook near Arches National Park. A traditional English-style mild ale with a well balanced malt to hop ratio."

Around 10 million years ago the Farallon Plate, a large plate that was subducted below North America off the western coast of the the US, began to push upwards on the region. As the region was forced upward, the rivers that were formally allowed to meander naturally, started to erode downwards into the underlying bedrock. This downward erosion locked the rivers in place, creating a feature known as an entrenched meander. This entrenched meander is what created the "point" in Dead Horse Point, where an entrenched meander created the outcrop of rock jutting outwards.  

Drunk on Mineralogy - Ruby Hard Cider

 

The next Drunk on Geology is for Ruby Hard Cider from the Mountain West Cider Company. 

Although often referring to the strong red color, the ruby is a gemstone that comes in a pink to blood-red hue. The name "ruby" comes from the Latin ruber, meaning red. A ruby is the red variety of the mineral corundum, whereas all other colors of corundum are known as sapphires. Corundum itself is an aluminum oxide mineral, with the chemical formula of Al2O3. 

Ruby crystals from wikigempedia.com

Corundum is one of the hardest minerals on Earth and serves as the 9 index mineral on Mohs Hardness Scale (of which a diamond is 10). This high hardness means many things about the mineral, one of which is that it is very difficult to erode, often being left behind after the host rock has eroded away, but also that it can be used readily as an abrasive. Corundum also has a very high specific gravity (density), especially for a non-metallic mineral, making it fairly easy to identify. Corundum is frequently found as a metamorphic mineral in marbles, gneiss, and schists but can also be found in igneous rocks such as granite and nepheline syenite. 

Looking at the ruby specifically, the red color is created by the addition of small amounts of chromium into the crystal structure. The color can be variable though, depending on the amount of chromium and iron, with the colors themselves often ending up being region specific. Terms like "Burmese" ruby for those found in Myanmar or "Thai" ruby for those found in Thailand are then sometimes used, but the color is not always a great indication of source. 

Natural rubies, however, are extremely rare. And even when they are found, they are often imperfect specimens that require heating and chemical treatments to perfect them for gem purposes. Because of that, artificial rubies are more often used for gemstones. Artificial rubies had been produced for over 120 years and produce very high quality looking gems for a fraction of the cost. 

Text on the back of the can:

"Ruby: the cider that started it all. We sold our very first bottle back in 2015 and it's been flying off the shelves ever since. This carefully-crafted traditional dry cider is complex, yet balanced and crisp, and pairs well with just about anything. Now that it comes in a can, we hope you and your friends will find fun new places to take it."

Rubies in marble from Vietnam. Image courtesy of irocks.com.

Historically, the places most well known for ruby deposits are in Asia, however they have been discovered well outside of Asia including Africa, Australia, and the United States. The most notable ruby deposits are in Myanmar, Sri Lanka, Thailand, Cambodia, Madagascar, Mozambique, Nepal, Afghanistan, and Vietnam. It is because of the rarity of the natural ruby, as well as the beauty that a perfect crystal possesses, that lends the natural ruby such a high price point, even if it had been heat-treated to remove flaws.

References
https://geology.com/minerals/corundum.shtml
https://www.wikigempedia.com/ruby.html
https://www.gemsociety.org/article/ruby-jewelry-and-gemstone-information/

Drunk on Paleontology - Soul Rex Double IPA

 

The next Drunk on Geology post is for Soul Rex Double IPA by Level Crossing Brewing Company out of Salt Lake City, UT. 

The Soul Rex is clearly an homage to one of the mightiest of dinosaurs, the Tyrannosaurus rex. As pictured on the can, the logo presents a stylized version of the T. rex in shades, a jazz type hat, and holding a bass. I had previously done a couple of T. rex inspired beers before for the Pseudo Sue Pale Ale and the Tooth and Claw Dry Hopped Lager. Both of those beers focused on one specific T. rex skeleton, SUE, located at Chicago's Field Museum. So for this one I will look at the T. rex in general.

The first Tyrannosaurus rex skeleton was discovered in 1902 by Barnum Brown, the then assistant curator for the Department of Vertebrate Paleontology at the American Museum of Natural History (AMNH) in New York. The bones, discovered in the Hell Creek Formation near Hell Creek, Montana, were identified by a local land owner who then told Brown. The skeleton, only 10% complete, took 3 years to excavate and was then transported to the AMNH where the paleontology curator of the museum, Henry Fairfield Osborn, named the fossil in 1905 Tyrannosaurus rex, meaning "Tyrant Lizard King". 

All fossils of the T. rex have since been found in western North America, ranging from southern Canada down into southern New Mexico and Texas. The T. rex was also one of the last living non-avian dinosaurs, having lived during the late Cretaceous period from about 68 to 66 million years ago, which is when the meteorite struck the Earth, wiping out those non-avian dinosaurs.

Although the skeleton discovered initially by Brown was only a partial skeleton, an even more complete skeleton was discovered by Brown 6 years later that became the basis for the skeleton seen above, mounted at the AMNH. It is this mount that went on to influence pop-culture for most of the next hundred years, where the T. rex was almost always portrayed in a vertical pose. Unfortunately this pose was set up mostly because of the steel armature could not do a more dynamic pose. Many of the tail vertebrae even needed to be broken in order to get the T. rex to be standing like this. 

It wasn't until 1993's Jurassic Park, that movie and tv makers really started to take a look at the advancing science behind the dinosaurs and adjusted their models accordingly. For the movie, the T. rex is presented in a much more accurate model, where the body of the beast is balanced over the legs, with the tail acting as a counterweight, forming a giant see-saw. This remodeled T. rex also gives us a much more accurate depiction of its size, where an adult can grow up to ~12 feet tall at the hip and ~40 feet long from tip of the tail to snout. But one of the most notable features of a T. rex were its teeth, that ranged in size up to 12 inches long, which included the root, still leaving approximately a 6 inch tooth exposed.

Text from the back of the can:

Soul Rex Double IPA - A hefty but cultured pint. Sweet notes bellow from a cellar cabaret... you're unwavering to behold who's onstage... as your eyes come into focus in the dark dank chamber... just so you know, he's got soul! This badass beer has a deep golden hue exposing a sophisticated world of tropical fruit whiffs with melon and citrus as the opening act. For the encore, stone fruit and juicy hop bitterness steal the show. This beet performs as intended, a highly drinkable brew to enjoy again and again.

Since the release of Jurassic Park, the science of T. rex has continued to advance. With the discovery that birds are descendants of dinosaurs, and many dinosaurs discovered with feathers, it is now believed that even the T. rex likely sported some variety of plumage, although it is currently unclear how much plumage a T. rex  may have had at any given point in its life. 

It is unclear how much this current model of the T. rex will change as more fossils are discovered and analyzed, but as one of the most famous dinosaurs, there are sure to be many people hunting for the next big breakthrough. Will those future discoveries include that T. rexes liked to hang out in jazz clubs and play the bass? The world may never know.  

References
https://www.fossilguy.com/gallery/vert/dinosaur/tyrannosaurus/trex-discovery.htm
https://www.smithsonianmag.com/science-nature/barnum-brown-the-man-who-discovered-tyrannosaurus-rex-70758588/
https://www.amnh.org/dinosaurs/tyrannosaurus-rex
https://www.mentalfloss.com/article/606903/how-t-rex-american-museum-natural-history-became-icon

https://www.businessinsider.com/t-rex-discoveries-hunted-walked-growth-2021-4

https://tulsaworld.com/location-of-t-rex-fossil-discoveries/image_e1f73009-69c9-5b57-87b8-f616d47a9950.html

Drunk on Geomorphology - Colterris Monumental Cabernet Sauvignon

 

The next Drunk on Geology is for Colterris Monumental Cabernet Sauvignon from the Colterris Winery in Palisade, CO. 

Colterris Monumental Cabernet Sauvignon features prominently the Balanced Rock of nearby Colorado National Monument. Balanced Rock, named on the bottle, is presented on the bottle by an absolutely striking picture of the rock being highlighted by, what I am assuming, is a sunrise. The picture is a painting by Colorado based artist John Lintott. 

Balanced Rock is part of the Wingate Sandstone, the dominant rock formation within Colorado National Monument. The Wingate Sandstone is Early Jurassic (~200 million years old) in age and was formed from eolian sandstone. This means that these rocks were sand dunes that were once part of a desert (eolian meaning "wind blown"). The rock is made up of nearly entirely of quartz sand grains glued together with a mineral known as calcite, or calcium carbonate. The Wingate also includes some slight amounts of iron oxide, otherwise known as hematite, or rust, which gives the rock it's characteristic yellowish-red hue. 

Over time, this formation was solidified from the sand dune into a sandstone. And then this sandstone was uplifted along with all of the other formations that lie both above and below it. These formations then started to undergo erosion, breaking down the rocks slowly over time through wind, water, dissolution of the cement, and frost action. Water works its way through natural joints, or fractures, in the rock. As the water works its way through the rock, it dissolves the calcite cement, much in the same way water dissolves the calcite of a cave. Then during the winter time, without the cement holding the rock together, the water freezes and expands, forcing the rock slightly apart. Over the course of many thousands and millions of years, that small degree of movement compounds and slowly the rock is broken up. Gravity then carries away the pieces broken off, slowly eating away at the cliff face. 

Differences in the bedding and joints in the formation preferentially direct the water into specific areas, creating isolated pieces of rock that withstand erosion better then other places. You can see the vertical joint along the right side of the rock that had preferentially been eroded, isolating the column of rock. This likely was sourced by water running off of the plateau that we can see the end of on the right hand side. With the separation of the Balanced Rock pillar from the plateau, water likely has more difficulty getting to the Balance Rock, and therefore prolongs its existence. 

Weathering/erosion also attacked the bedding plane below the the Balance Rock, which eroded more than the overlying ball of rock. This same bedding plane can be traced back to the cliff face itself, where that same layer was also eroded more than the overlying rock. It is likely that those weaker areas of the rock also have higher amounts of erodable minerals like clay. 

The question on the display asks the most pertinent question of "How will Balanced Rock eventually topple?" but they do make note to point out that Balanced Rock is a snapshot in time that we are privileged to be able to witness. 

References

http://npshistory.com/publications/geology/bul/1229/sec1.htm

Drunk on Volcanology - Crater Lake Oregon Chardonnay

 

The next Drunk on Geology is for Crater Lake Oregon Chardonnay by Eola Hills Wine Cellars in Rickreall, Oregon.

We had visited Crater Lake National Park over the summer of 2019 and we able to pick up this wine during dinner in the main lodge. Then afterwards I took some pictures out the back patio of the lodge overlooking the lake with Wizard Island in the background, matching the view on the bottle itself.

Crater Lake is a volcano located along the Cascade Range in the Pacific Northwest of the United States, which runs north into British Columbia in Canada. Crater Lake was originally a full blown volcano known as Mount Mazama, which was ~12,000 feet high before it erupted ~7,700 years ago. 

Some of the major volcanoes along the Pacific Northwest.  Image courtesy of the USGS. 

These volcanoes formed from the process known as subduction where one of the Earth's crustal plates descends slowly below another plate. As the denser plate descends, it begins to melt. The melted rock then rises up through the crust creating a line of volcanoes known as a volcanic arc. Crater Lake is one of the volcanoes located along the Cascadian volcanic arc.

Diagram illustrating the process of subduction. Image courtesy of the USGS.

Mount Mazama, like Mount Tehama to the south that eventually eroded into Lassen Peak, was a composite volcano. There are lots of different types of volcanoes. A composite volcano is a volcano that is composed of  alternating layers of ash, lava flows, rock fragments, and cinders that slowly piled up over time from smaller eruptions. The primary type of magma in this volcano was the thicker magma, termed felsic, that has a higher silica and gaseous content than volcanoes in places like Hawaii. Felsic magma and lava has a tendency to flow slowly and also to clog up volcanic vents. This periodic clogging allows the volcano to build up pressure, both from the thick lava and the high gas content within the volcano. It is like a soda bottle being shaken before the cap is released. Around 7,700 years ago the cap was released, producing an enormous eruption that released ash, gas, rocks, and lava into the air and surrounding regions. Eventually the magma chamber mostly emptied, leaving a gaping void below the mountain peak, which collapsed in on itself. This formed a bowl shaped depression known as a caldera. Later, smaller eruptions sealed the caldera floor, allowing for water to accumulate over time.

Crater Lake is one of the few volcanic calderas that are fully isolated from the surrounding water environment. Water only leaves the lake through evaporation, and a small amount of seepage, while it only enters the lake through snow and rainfall, keeping the lake at a nice balance. The lack of streams into the lake has also nearly eliminated the sediment within the lake, producing a crystal clear lake that reflects the deep blue of the sky. 

.

Text on the back of the bottle:

Located in South-Central Oregon, Crater Lake has inspired visitors for thousands of years.

Crate Lake is a place of immeasurable beauty and a reminder of the land's volcanic past. No place else on earth combines a deep, pure lake, so blue in color, with sheer surrounding cliffs reaching towards the sky. 

Seen on the bottle label, as well as in the background of the photos, is Wizard Island, which is easily the largest island in the lake. Wizard Island was formed during the subsequent eruptions shortly after the formation of the caldera. Wizard Island is a cinder cone. A cinder cone is another type of volcano that is produced when lava splutters out of a volcanic vent. As the lava is spit into the air is cools and forms a type of rock that is usually smaller in size and has a lot of air holes called scoria. During the course of the eruption these small chunks of rock pile up around the volcanic vent and eventually pile up to form a cone. The cinder cone Wizard Island is over 700 feet high from the surface of the water. 

Drunk on Volcanology - Lassen Peak Tres Rojas

 

The next Drunk on Geology is for Lassen Peak Tres Rojas by the Lassen Peak Winery.

We were able to pick up some of the Lassen Peak Winery bottles from the gift shop within the Lassen Peak National Park while we were there. I took these pictures from Butte Lake Campsite in the northeastern corner of the park. 

Lassen Peak is the remnant of a once much larger volcano, Mount Tehama, that erupted leaving behind a 2 mile wide caldera located between the surrounding mountains of Lassen Volcanic National Park.

Map of west coast subduction zone volcanoes. Image courtesy of the USGS.

Lassen Peak is the southernmost volcanoes in the Cascade Range, a series of volcanoes that stretch up into Canada along the Pacific Northwest coast.  These volcanoes formed from a process called subduction. The crust of the Earth is broken up into very large pieces called plates. These plates move around, with some sliding past each other, some pulling apart from each other, and others going towards each other. The edge of these plates are where earthquakes frequently occur, due to the rubbing of the plates against each other. 

Illustration of a subduction zone. Image courtesy of the USGS.

When a plate composed mostly of oceanic crust goes toward a plate composed mostly of continental crust, the denser oceanic crust gets forced downwards into the Earth. This area is known as a subduction zone. As the denser oceanic plate moves downwards into the Earth it starts to heat up and eventually melt. That liquid rock rises up through the crust forming a string of volcanoes called a volcanic arc. The Cascade Range is such an arc with Lassen Peak representing the southernmost extent of the subduction zone. 

There are many different types of volcanoes. Here is a view of Lassen Peak in the distance, rising up to 10,457 feet in elevation. It is so high that during our trip at the end of June it is still entirely covered in snow. Lassen Peak is what is known as a "Plug Dome", this forms when the lava is too thick to flow great distances. Lava rich in silica (quartz), has a higher viscosity (thickness) and doesn't flow as far as thinner, basaltic magma, which is hotter and has less silica content.

Lassen Peak can also be viewed on the front of the wine bottles. The original Mount Tehama was known as a "composite volcano", which means that it was composed of alternating layers of ash, lava flows, rock fragments, and cinders that slowly piled up over time from smaller eruptions. Most of the volcanoes in the Cascades are composite volcanoes. Mount Tehama was active with frequent eruptions from about 600,000 to 400,000 years ago until the magma shifted and the volcano, losing its magma, started to collapse and erode away.

Once we reached the highest part of the road way at Lassen Peak, the snow really was still piled up. Here is a view of the snowfields along Lassen Peak at ~8,500 ft.

Despite the larger Mount Tehama having eroded away, the area is still very much volcanically active. Within the central part of the caldera, towards the bottom of the valley between the mountains, is a large hydrothermal area. The hydrothermal area contains many features that are heated up from the rich source of magma that still resides below the surface. This particular area is known as the Sulphur Works, which does have that glorious rotten egg smell, but there are a few other hydrothermal areas within the park. Hydrothermal features also have a tendency to have very vivid colors from the heavy minerals that get brought to the surface by the groundwater from the magma.

Text from the back of the bottle:

"Tres Rojas is our finest Red wine, made from a Reserve blend of three Bordeaux varietals, Cabernet Sauvignon, Merlot, and Cabernet Franc.

Our vineyards and winery are located in the mountains midway between Lassen National Park and Redding, CA, nestled in majestic pine forests. Our 2600' elevation, volcanic soils, steep terrain, and natural spring water provide ideal conditions for growing winegrapes. We use natural years fermentation in small French oak barrels to handcraft our rich and flavorful wines full of varietal character." 

Drunk on Paleontology - Pearadactyl Pear Apple Wine

For my next Drunk on Geology we have Pearadactyl - Pear Apple Wine by the Carlson Vineyards in Palisade, Colorado. 

Clearly named after the word Pterodactyl, the name of the wine takes advantage of the similar sounds between the the "Pter" (pronounced like tear) and the rhyming "pear". But the word Pterodactyl was first coined in 1809 by Georges Cuvier. This was based on a fossil of an unknown creature first identified in 1784 by Italian scientist Cosimo Collini, who though this must be a marine organism of some kind. Cuvier correctly discerned later that this was a flying animal and coined the phrase "Petro-dactyl" meaning "winged finger":

"Sur le squelette fossile d'un REPTILE VOLANT des environe d'AICHSTEDT, que quelques naturalistes ont pris pour un oiseau, et dont nous formons un genre de SAURIENS, sous le nom de PETRO-DACTYLE."

"On the fossil skeleton of a FLYING REPTILE from the environe of AICHSTEDT, which some naturalists have taken for a bird, and of which we form a genus of SAURIANS, under the name of PETRO-DACTYL."

Cuvier's 1812 drawing of the first "Petro-Dactyl" specimen. Image from Recherches sur les ossemens fossiles de quadrupèdes. t. 4 (1812). https://www.biodiversitylibrary.org/page/40032094#page/677/mode/1up.

A Latinized version of Cuvier's descriptive term for the animal was then used by Lorenz Oken in 1818 to name the animal with the official species name of Pterodactylus. Since that time, the term "pterodactyl" is not actually a scientifically valid name. The group of flying reptiles is collectively known as "pterosaurs", which are all the animals that belong to the taxonomic order Pterosauria. Within the order of Pterosauria, there are individual animals such as the Pterodactylus and the Pteranodon, but nothing that would be referred to simply as a "Pterodactyl". 

Reconstruction of the Pterodactylus. Image courtesy of the the Dinopedia Wiki Page.

But despite the misnomer, the name lives on, as anyone who has tried to Google the animal can attest to. Overall, pterosaurs are a group of flying reptiles. They are NOT dinosaurs, having branched off of the reptile family tree before dinosaurs had truly evolved. You can think of them as the cousins of dinosaurs. These flying reptiles were the first vertebrates to have evolved powered flight with some species having grown to tremendous sizes. The largest pterosaur, Quetzalcoatlus northropi, stood 16 feet tall and had a wing span of 33 feet, which is the size some airplanes. They flew using a skin and muscle membrane that stretched across the first three fingers of their hands as well as between their shoulders and wrists to their hind limbs, creating their wings. Some pterosaurs also had the membranes between their legs.  

Life sized reconstruction of a Quetzalcoatlus northropi at Chicago's Field Museum from the Late Cretaceous

The group of Pterosaurs lived from 228 to 66 million years ago, going extinct at the end of the Cretaceous along with the non-avian dinosaurs when the asteroid hit the Earth. It is theorized that these animals were possibly warm-blooded with some (possibly all?) having a furry coating of hair-like filaments over their bodies. 

Trackway of a small pterosaur showing both the fore- and hind-limbs of the animal. Image courtesy of Scientific American. 

As pictured in the reconstruction above, pterosaurs are also known to have walked on all four limbs. Scientists know this from, not only reconstructions of the skeletons, but also fossilized trackways that preserved the hand imprints along with the feet.

Text from the back of the bottle:

"Carlson Vineyard's Pearadactyl is a 100% western Colorado grown, semi-sweet pear-apple wine best served chilled with light foods and good friends. If you close your eyes real tight and think very hard about the way it was 160 million years ago, you just might see a Pearadactyl gliding by with a delectable pear in its beak."

Looking that the Pterodactylus itself, this species of pterosaur lived during the Late Jurassic period, approximately 150 million years ago. This matches fairly closely with the wine's listing of "160 million years ago". 

The bottle also mentions that the Pearadactyl would have been gliding by with a "delectable pear" in its beak. Pears, and pear tree in particular, belong to a group of plants known as angiosperms. Angiosperms include all of the flowering (and fruiting) plants that we know of today. Early angiosperms are thought to have evolved in the Early Cretaceous or the Late Jurassic, ~140-250 million years ago (Nature). Along with the evolution of the flowering plants, is the evolution of the fruit that they bear. 

The pear fruit is a result of the domestication by humans of the pear tree and the cultivation over human history. The plant itself belongs to the Pyrus genus, which is estimated to have evolved only a few 10's of millions of years ago. However, it belongs to the larger group of the Rosaceae family of fruit trees. The Rosaceae family evolved ~100 million years ago, with several ancestral fruit bearing trees having existed alongside the dinosaurs and pterosaurs during the Cretaceous period. This means that although the "pear" would not have been present alongside the "Pearadactyl", perhaps an ancestral fruit would have been.

References

https://blog.biodiversitylibrary.org/2015/10/identifying-first-flying-reptile.html
https://www.biodiversitylibrary.org/page/29092318#page/423/mode/1up
https://www.biodiversitylibrary.org/page/40032094#page/677/mode/1up
https://www.livescience.com/24071-pterodactyl-pteranodon-flying-dinosaurs.html
https://dinopedia.fandom.com/wiki/Pterodactylus
https://www.scientificamerican.com/article/footprint-find-could-be-a-holy-grail-of-pterosaur-research/
https://academic.oup.com/mbe/article/34/2/262/2528249