18th July 2025: In the University of Saragossa {Dinosaur Eggs Loarre & Zaragoza, July 2025}

I woke up and for the first time in days I put on “person clothes” (for the city) instead of “scarecrow clothes” (for hiking & working in the field). Before setting off on the trip, I went to the sales to buy some jeans that would work for sitting on rock or walking through thistles and dry grass, and while they are not particularly nice, they are comfortable and resistant. Saragossa / Zaragoza was still waking up as I headed for breakfast to a bakery close to the hotel, Pannitelli Original Bakery, which I had chosen for two reasons. One, they opened at 7:30, which gave me plenty of time to walk to the university afterwards and two, they had waffles, I had seen them online. I wanted waffles, and a big coffee. I had both (and some orange juice, just because I could).

It turned out that not driving to the university Universidad de Zaragoza had been a great idea. Though it had been my first thought (dump the car there, then walk to my accommodation), I was lucky that in the end I was able to reserve my parking spot with the hotel. It happens that access to campus is restricted to working staff. Students can drive into the parking lot ten times in the school year. And on top of that, there was a farmers’ market for some reason.

Having 20 minutes to walk, I was the first one there, and I sat down in the rock garden of the Earth Sciences building to wait for everyone else for the last day of the course Técnicas de restauración en paleontología a través de la preparación de los huevos de dinosaurio de Loarre: Palaeontological Restoration Techniques through the preparation of Loarre dinosaur eggs. By 9:00, when class was to start, I was the only one besides the teachers who had managed to arrive. Everyone else had either got lost, left Loarre late, or was taking forever trying to park. So yay me being lucky for once (and for the 20 € which the hotel parking cost for the whole stay).

The first chunk of the morning was a tour through the Rock and Hard Material Preparations, 3D Printing and Scanning Service (Servicio de preparación de rocas y materiales duros, impresión y escaneado en 3D) in the university. They have two main lines of work. One is to make thin translucent sections out of specimens so they can be studied under the microscope, and the other is digitalising and making 3D models and copies of items so they can be lent or studied through a computer. The inner works of the department were explained by Raquel Moya Costa, who not only described in detail all her complex machinery, she also gave each of us a 3D printed T-Rex charm from the Dino Run Game!

We then moved onto the Petrology lab to look at thin sections on the transmitted-light microscopes – preparations of a sauropod eggshell, a crocodilian eggshell and an iguanodon eggshell. There were other preparations we could snoop around if we promised not to take pictures and publish them. We also got to play with the 3D copy of one of the first eggs recovered from Loarre. Much less heavy than the real thing, for sure.

Microscope used in geological studies

Microscope preparations and how they look under the microscope. There are three egg specimens: one from Loarre (sauropod), a crocodile and an iguanodon, The crocodile is the thinnest, and the sauropod is the brightest and more complex

Then a bit of chaos ensued as we got distracted by the shiny exhibits of the Palaeontology department, and a couple of post-docs offered to show us their lab and what they were working on. Having finished all the activities of the course, the coordinators had organised an extra visit to the Natural Science Museum Museo de Ciencias Naturales de la Universidad de Zaragoza (which might have actually been my fault as I asked how come that would not happen, considering that most of the region’s fossils are officially deposited there). A few people left first, but some of us got delayed looking at the lab specimens, and then we had to hurry to the museum…

Zaragoza Natural Science Museum: Exhibits in the Geological science building. Replicas of dinosaurs and invertebrate fossils

Once we were at the site of the Museo de Ciencias Naturales, we were taken on an express visit of the palaeontology ward by Ester Díaz Berenguer, curator of the collections. The museum is located in one of the historical buildings of the Zaragoza campus. Designed by Ricardo Magdalena in 1886, it was erected with academicist criteria, in brick, with large windows and striking symmetry. It opened in 1893, and during the 20th century, it served as Faculty of Medicine. When the university moved to the newer campus, the building was refurbished as cultural spot and seat of the government body. The basement was turned into the exhibition site of the Science Museum, which has three main areas – palaeontology, natural science, and mineralogy.

The palaeontology ward of the museum comprises nine rooms. The first one is an introduction to the science and the concept of fossilisation, and the following ones run through the Earth’s history, from the Precambrian to the Quaternary. The Precambrian is the earliest “calculated” period in geological time, and spanned from 4567 to 539 million years ago (give or take). Though we cannot pinpoint when life actually originated, it was already there when this “supereon” gave way to the Cambrian. During the Ediacara Period, at the end of the last Eon of the Precambrian, the Proterozoic, the earliest complex multicellular organisms that we know about thrived in a state that has been called “The Garden of Ediacara”. The word “garden” tries to evoke the idea of the “Garden of Eden” as there was no active predation and life just… existed.

The next rooms focus on the “Cambrian Explosion”, a term used to refer to the point in geological time when living things took over the planet. At first, this brand-new life was comprised of ocean-dwelling invertebrates. In the room there are impressive trilobites from the Murero Palaeontological Site, which I had actually planned to drive through on my way back. But not only animals appeared, so did plants – organisms which produced a new toxic gas that would change the planet forever: oxygen. To the side of this area there is a curtained room, the “aquarium”.

Zaragoza Natural Science Museum: Two trilobites from the same species showing slightly different shapes, thought to be a male and a female

Here you can see the cranium of Carolowilhelmina geognostica, a fish which lived around 392 million years ago, during the Devonian period. It was a placoderm, a group whose main characteristics were being covered in armoured plates, and having developed an actual jaw and true teeth. The specimen is not just the holotype, it is the only known fossil of the animal. The cranium alone measures almost 45 cm, and by its shape, palaeontologist speculate that the animal was probably a predator of invertebrates. A first fragment of the fossil was found in Southern Aragón in 1971 by palaeontologist Peter Carls. Carls kept returning to the site to search for the rest of it every summer, until in 1986 he unearthed the rest of the skull, which was finally extracted in 1993.

Zaragoza Natural Science Museum: skull of an ancient armoured fish

The following room is devoted to the Mesozoic, and it hosts another of the museum treasures, the skull of the holotype and only specimen of Maledictosuchus riclaensis, the “Cursed Crocodile from Ricla”. This crocodilian lived in saltwater around 163 million years ago, during the Middle Jurassic. It had flippers instead of legs, and probably ate fish. The fossil was found during the construction of the high-speed railway between Madrid and Barcelona in 1994. It earned the name of “cursed crocodile” because despite the fact that it was the oldest crocodilian found in Spain, exceptionally preserved on top of that, it took 20 years until someone could tackle its study and description. The “curse-breaking” researcher was Jara Parrilla Bel, one of the post-docs who shown us her lab work at the university.

Zaragoza Natural Science Museum: Skull of an ancient crocodile

Of course, the “stars” of any palaeontological exhibit are dinosaurs. The museum hosts several iconic pieces, amongst them replica of the feet of the first dinosaur ever described by researchers belonging to the local university Universidad de Zaragoza, Tastavinsaurus sanzi (a titanosaur), a whole specimen of the Mongolian Psittacosaurus (a small ceratopsian), and a good part of an Arenysaurus ardevoli, a hadrosaur which lived in the Pyrenees area around 66 million years ago, during the early Maastrichtian; the rest of the specimen is located in Arén, where it was located, and which is one of the museum’s satellite centres, just like Loarre’s museum-lab. In the same room there were trunks of fossilised wood that could be touched, and a skull of the extinct crocodile Allodaposuchus subjuniperus.

Zaragoza Natural Science Museum: Skeleton of a small Mongolian dinosaur

Zaragoza Natural Science Museum: some bones from a hadrosaur, including the tale, hind hip and some ribs

After a small room with an audiovisual representing the impact of the meteorite and the K-Pg mass extinction (which we skipped due to time constraints), there was an exhibit of the spread of mammals. The specimen of honour in this exhibit is the ancient sirenian Sobrarbesiren cardieli (holotype, and the topic of our guide’s thesis). This species lived during the Eocene, around 45 million years ago. Sirenians (manatees and dugongs) are a type of marine mammals whose closest relatives are elephants – and not other ocean-dwelling mammals. After life spread through land, a number of mammals went back to water, and it looks like this species is a snapshot on the readaptation process: it was already completely aquatic, but it still had four functional limbs. Its hind legs had started reducing and its tail was getting flat. It was a strict herbivore, eating sea grass, but less efficiently than current sirenians.

Zaragoza Natural Science Museum: Skull of an ancient sirenian.

There was also an impressive aquatic turtle of the genus Chelonia, several remains of Gomphotherium angustidens, an elephantimorph, and smaller pieces including crabs, sea urchins, gastropods and even insects. Several of these specimens are holotypes, too.

The final area was almost contemporary considering when we had started. It hosted remains of cave bears (Ursus spelaeus, 40,000 years ago), the skull of an aurochs (Bos primigenius, a species that actually lived until the 1600s), evidence ancient hyena nests, micro-invertebrate bones, mammoth defences… These animals coexisted with human beings, whose skulls comprise the ending room before moving onto the “nature collections” which we did not visit because a) the course had after all to do with palaeontology and b) it was closing time – quite literally, museum security was turning off lights behind us since the museum shut down at 14:00.

Zaragoza Natural Science Museum: Skull of an ancient bull, curved mammoth defence, a pile of bones from a hyena nest and several human-ancestor skulls

We had a mini closure “ceremony” in the hall of the building – coordinators Miguel Moreno Azanza and Lope Ezquerro Ruiz thanked us for attending, we clapped and thanked them back. Then we all went off to have a drink, a snack and a chat. A bit after 16:00, when most students had already left and the professors had been joined by university staff, I took my leave.

Palaeontological Restoration Techniques through the preparation of Loarre dinosaur eggs

Hopping from shadow to shadow to avoid the sun and the heat as much as I could, I headed downtown. On my way I made an exception regarding the walking in the shade when I found the only remaining gate of the original Medieval Wall, today called Puerta del Carmen. Calling it “original” is a bit of a stretch though. While it is in the same place as the first gate, it actually dates from the early 1790s, and it follows Neoclassical patterns.

I also stopped at Starbucks for a Vanilla Frappuccino – I’m on a bit of a matcha remorse trip due to the alleged shortage, so I’ve reverted to my old drink of choice. With a temperature of around 38 ºC, I reached the most important square in town, Plaza de Nuestra Señora del Pilar, where the namesake basilica is. I kid you not, what was running through my head was “I’ve got a 0.5 zoom on my phone now, I’ll be able to take a nice picture of the whole building with its towers…”. Only to find said towers covered in scaffolding. I was able to take the picture, but it could have been nicer. I entered the Cathedral-Basilica of Our Lady of the Pillar Catedral-Basílica de Nuestra Señora del Pilar, a Baroque / Neomudejar catholic temple which is considered the first-ever church dedicated to the Virgin Mary. I sat at the chapel for a little bit, but when I was ready to have a walk around the church, there was a call for mass, so I did not do it out of respect.

Chapel of Our Lady of the Pillar, a baroque chapel for the workshop of a small figurine of the Virgin Mary carrying a child and standing on a pillar

Instead, I strolled to the former exchange building Lonja de Zaragoza, which has been turned into a free exhibition centre. The building is Renaissance with a touch of Neomudejar, and it is considered the most important civil architecture construction erected in the whole area of Aragón during the 16th century.

I had read that there was an exhibition on Asian culture called Tesoros. Colecciones de arte asiático del Museo de Zaragoza – Treasures: Asian art collections from the Zaragoza Museum. At the moment, the Zaragoza Museum is closed and has loaned a few of its artifacts to be displayed elsewhere. This one exhibition displays items that were originally part of personal collections and were donated to the museum. The Colección Federico Torralba, comprises religious items and art pieces from China and items from Japan. The Colección Víctor Pasamar Gracia and Colección Miguel Ángel Gutierrez Pascual have woodblock prints – landscapes, noh [能], kabuki [歌舞伎], even modern ones. The. Finally, the Colección Kotoge displays lacquered tea bowls (chawan [茶碗]). There are also modern calligraphies, paintings, and the compulsory samurai armour. The regional government has undertaken buying artefacts to engross the Asian collections. Though they looked a bit out of place in the historical building, the items were fantastic – and you could even make your very own “woodblock print” at the end.

Zaragoza exchange ceiling, decorated with architectural flower-like patterns

Though the exhibition was the reason I had wanted to go downtown, after I left the (nicely air-conditioned) Lonja, I still had some time to do stuff. I wandered back into the cathedral for a bit – between the 17:00 mass and the 18:00 mass, and left before the second one started.

I continued towards the Roman Walls Murallas Romanas de Zaragoza, which sadly have had to be fenced off because people have no respect (I vividly remember a mum letting her toddlers to climb all over them one time I visited). At the end of that square stands the marketplace Mercado Central de Zaragoza, a wrought iron architecture building designed in 1895 by Félix Navarro Pérez. Being a Friday evening, in the middle of summer, many of the stands were closed, so it was not crowded.

Zaragoza Roman ruins

Iron and glass architecture market

I continued towards the Fire and Fireforce Museum Museo del Fuego y de los Bomberos, where a nice gentleman wanted to give me a guided visit which I declined. Honestly, I just wanted to look at the old fire trucks (and actually, support any initiative by firefighters if it helps fund firefighting). It is a little quaint museum located in part of a former convent, the other half is an actual fire station. The exhibition covers documentation of historical Zaragoza fires, firefighting equipment, a collection of helmets, miniatures, and quite an impressive collection of vehicles used to fight fire. There were two immersive rooms, one which showed damage to a house and another about forest fires. I really enjoyed it, though I only had a quick visit – they closed in an hour, and I was the only guest along a family.

Firefighting museum: collection of vintage vehicles in a brick cloister

On my way back towards the hotel I walked by CaixaForum Zaragoza, where they were running the Patagonian dinosaurs Dinosaurios de la Patagonia. Seeing the Patagotitan on the balcony made me want to go in, but I had already seen it, and I knew I was just on a palaeontology high.

Patagotitan installation on a balcony

I headed back to the hotel – crossing a couple of quite unsavoury neighbourhoods – and bought some fast food dinner again. It was stupidly early, but after eating I could have a shower and relax on the bed while I studied the route for the following day. Furthermore, it was so hot I really needed that shower, and I knew I would not be going anywhere after taking it. Thus, I showered and plopped down to watch the Natural Science Museum’s YouTube Channel after I had learnt how to get out of the city.

16th July 2025: Santa Marina Palaeontological Site {Dinosaur Eggs Loarre & Zaragoza, July 2025}

In our second morning in the Loarre course Técnicas de restauración en paleontología a través de la preparación de los huevos de dinosaurio de Loarre: Palaeontological Restoration Techniques through the preparation of Loarre dinosaur eggs, we met at 9:00 in the museum-lab Laboratorio Paleontológico de Loarre. The first thing we did was pick up our PPE – glasses, earplugs, facemask and work gloves. For the day we would be cared for by Miguel Moreno Azanza, Lope Ezquerro Ruiz, Ester Díaz Berenguer, Manuel Pérez Pueyo and Laura De Jorge i Aranda.

Miguel Moreno Azanza and Lope Ezquerro Ruiz are the course coordinators. The former is holds a PhD in Geology and is a Postdoctoral fellow in the Saragossa university Universidad de Zaragoza. He is the egg expert and the leader of the works in Loarre. Ezquerro Ruiz is now a Lecturer at another University, Universidad Complutense (Madrid), but he has not lost contact with the dino-egg world. He is the expert sedimentologist, described as an “all-terrain geologist”. Ester Díaz Berenguer did her doctorate about ancient manatees, once dug a sauropod skeleton all by herself, and is the Natural History collection curator in the Natural Science Museum of the University in Saragossa. Manuel Pérez Pueyo holds a postdoctoral position in the university Universidad del País Vasco and is currently away in Romania, studying the same kinds of sediments the Loarre eggs are found in – he is the K-Pg Limit expert. And finally, Laura De Jorge i Aranda is the de facto boss – she is the main restorer and conservation expert in the lab, so what she says, goes. If she ever stays still for long enough to finish saying it, because she must be related to the Duracell bunny…

We hopped onto the vans, and drove / bounced off towards the actual palaeontological site: Yacimiento de Santa Marina, the outcrop where the eggs were first found. Around 6 km away from the village, the area of the site is around 500 square metres, and eggs could be found from the surface (originally, those have been excavated now) to almost 2 m deep. It is mainly comprised of red clays hardened into actual rock, whose age is disputed between around 70 and 66 million years ago. Fragments of egg shells can be found on the surface, easy to tell apart. While the clays are mainly reddish, the egg shells are dark grey / blue, three millimetres wide, clearly rounded and with clearly-visible pores on the outer surface. And no, finding one of the dozens of them that we saw never got old. They have found six or seven groups of eggs there, so the upcoming steps are extracting them and working out if the groups are actual nests or just casual accumulations due to transport or other causes.

Yacimiento de Santa Marina - red hard unforgiving rock full of dinosaur eggs if you dig hard enough

There were three jobs to do around the site – cleaning up an area where eggs had already been found to check for more, repairing a cast jacket which had been damaged, and extracting a cast jacket which was ready to be transported to the laboratory. I started with the clean-up team. There, we used the “small” equipment (cleaning brushes, paintbrushes, and screwdrivers) to remove sediment and small rocks trying to see if there were more eggs around or underneath the one that had been removed. It was a definite maybe.

A spot in the ground where an egg was found. It has to be cleaned (swept) to check if there are more eggs or eggshells

The professors had brought Coke, Aquarius and pastries for breakfast at the mountain hut next to the hermit church Ermita de Santa Marina, which lends its name to the site, and thus we had a break around noon – the museum-lab team had brought us snacks and drinks. Afterwards, my group moved onto recasting a jacket which protects what could be a whole nest inside. The whole thing is massive and thus heavy, so difficult to move. While the logistics for that are being taken care of, the cast jacket protects the fossils inside, and the whole thing is kept buried to prevent weathering.

In Spanish, the cast jackets are called momias, mummies, as they are wrapped in gauze or similar before. Unfortunately, that degrades with time and weather. In order to protect the fossils, three of us applied a layer of cellulose (read: wet toilet paper) first, while the other two made burlap stripes that would go between the cellulose and the plaster. Later, another group would make and apply the new cast, and the following day the professors came back the next day to rebury it for extra protection.

Giant cast protecting fossil eggs before and after getting some TLC and new plaster

My group’s final job was breaking a plaster cast off the ground. As we worked on the other two spots, the other groups had taken a hydraulic hammer and a giant drill to the rock surrounding the cast to get it ready for extraction.. I got to work on the drill – while one of my peers pushed the tool into the rock, I was in charge of keeping the drill bit steady. Afterwards, I could hammer one of the stone-splitting wedges into the holes we had drilled, and a group-mate hammered in the other two. The cast was labelled and extra information was written on it: level, north, which side was up. After that, the whole thing was torn off the stand (by sheer blunt force, aka someone pushing it) and rolled onto a net that had to be hauled up the outcrop and then into the van, all that under the incredulous look of a herd of free-range cows which grazed nearby.

Jacket cast of a fossil being broken off the ground with a giant drill, and then transported using a net.

Two cows grazing

The strongest people around loaded the cast and carried it out, then put it in the van. They needed someone to take pictures of the process and I volunteered for that. By then, it was way past 14:30, which meant we were too late to have lunch in Loarre, where apparently it is only served between 14:00 and 15:00. Calls were (sort of desperately) made to find somewhere which would feed our large group lunch. We ended up in the restaurant at the campsite Camping de Loarre, which happily let us have some food there. They offered stuff to share, but we preferred to have individual plates. I think we all wanted something we really… wanted, so we just chose from the main dish options.

I ordered fried eggs with ham and chips. While I prefer my eggs runny, they were adequate. Since I had drunk a Coke for breakfast, I had an isotonic drink instead, and some of the communal water. As I was finishing, I overheard that they had ice cream inside… watermelon ice cream. It was exactly what I needed for dessert. While I was paying, the waiter asked something about whom to charge for the water, so I took care of that. It was still cheaper than buying all the soda and snacks the professors ended up providing.

Camping de Loarre: eggs with ham and a view of the castle

After lunch, we headed back towards the village, where we had a lecture by Laura De Jorge i Aranda on the theory of fossil restoration, conservation and preservation. One of the most important things she mentioned was documentation – as we had seen with the cast we had broken off. Once in the laboratory, the plaster is opened, the sediment classified for later study, the eggs cleaned mechanically and chemically, and any crack sealed with special glue. Every step of the way is documented. Finally, the fossils have to be packed for transport or preservation, and the sediment must be combed for anything of interest it might be hosting, such as loose egg shells (from either titanosaurs, crocodilians or theropods).

We moved then to the museum-lab to apply what we had just learnt in our first hands-on visit to the restoration laboratory. We were provided with a bunch of fossils (newly-discovered spinosaurid bones, so new that they are unpublished and thus cannot be shown) and Ester Díaz Berenguer guided us to make fossil beds with polyethylene covered with tissue. These were to go into fireproof drawers for conservation in the Natural Science Museum in Saragossa. The fossils are laid out on the polyethylene, traced, and the bed is carved for them with scalpels and cutters – remembering to also carve spaces for fingertips, so picking up the item is easier in the future.

A tray with cuts to fit the different fossil bones that we cannot show for scientific reasons, so it just looks like we cut a bunch of holes with weird shapes

After that, Miguel Moreno Azanza showed us some of the prepared eggs. One of the specimens was a couple of eggs stored together (one of them might have a baby inside!). These were found in another site, Collado de la Tallada, which apparently is “easier to dig in”, but we were playing level pro in Santa Marina. Another was a group of five eggs together, which could have been a nest. They are criss-crossed by mini-faults. We were able to snoop around other eggs, as the professors chuckled something like “Don’t worry, you’ll work on them tomorrow”.

Two titanosaur sauropod eggs in a case. They look about as big as the palaeontologist's hands each. They are deformed and broken but have a vague egg shape.

When I signed up for the course, I expected that the “practice” would be standing there while an expert did something. Maybe we would all get one egg shell to touch and share amongst us. That would have been really cool already. But by now I had dug, protected, drilled, pushed, and held fossils. I was ecstatic. The course had blown up my mind already, and there were still two and a half days left.

A titanosaur sauropod egg nest with five or six eggs, deformed and cracked by the passing of time.

I went back to the hotel Hospedería de Loarre to shower, have a snack, and pack all my things as I had to clear the room the following morning. I also studied off the route to get to Saragossa in the evening after the course. During the planning stage, I had considered whether I wanted to go to Saragossa on Friday morning before the lessons or Thursday evening after them, and in the end I decided to drive on Thursday.

On the one hand, it meant driving after the whole day of class, probably tired, and around dusk. On the other hand, it allowed me to do the drive without a time limit constraint, park directly at the hotel, and it might mean less traffic. Furthermore, sunset was at 21:00, and it should be bright enough for a bit still after class. In the end, I decided in the end that it would be less stressful. Thus, Wednesday was my last night in Loarre.

Palaeontological Restoration Techniques through the preparation of Loarre dinosaur eggs

15th July 2025: The Egg Museum & the Mallos {Dinosaur Eggs Loarre & Zaragoza, July 2025}

I woke up around 7:30. After I had stressed out so much about reaching there, I almost could not believe I was really in Loarre, at the feet of the Pyrenees mountain range. I lounged around until breakfast started at 8:30. I went down and the choice was limited but adequate – fresh bread (still warm, the bakery was literally under my window, and it had been making me hungry for an hour), tomato spread, Spanish omelette, cheese, sausages, pastries, coffee, milk, and an assortment of jams and butter. The coffee was weak, so I had a couple of cups, but the orange juice was freshly squeezed and awesome. I made myself toast with cheese and omelette, loaded up on the caffeine and went on my way. At 8:58 I was at the museum-lab Laboratorio Paleontológico de Loarre (Oodinolab). And there was my name, on the attendance sheet for the course Técnicas de restauración en paleontología a través de la preparación de los huevos de dinosaurio de Loarre: Palaeontological Restoration Techniques through the preparation of Loarre dinosaur eggs. Everything was going to be all right. I have to admit I was 100% ready to show all my emails and confirmation should any problem have arisen… but it was all right (which… I should have known due to the email received previously… but I am an overthinker by nature).

After signing attendance and checking details for the certificate, we received a tote bag with postcards, notebooks and pens. The course started with a welcome and introduction by Miguel Moreno Azanza, who is the Universidad de Zaragoza researcher in charge of the lab. The most important goal of the course, he transmitted, was empowering us with knowledge about every step involved in fossil-handling: from digging to commercial exploitation, including geology, conservation, restoration, study and museumification.

The course kicked off with the guided visit of the museum-lab that is usually done for kids and families, including pulling out crates for our backpacks. Thus we learnt about the story of the discovery of the eggs – a fellow researcher of Moreno Azanza’s, José Manuel Gasca, a geologist, runs mountain trail. In 2019, he was training with a few colleagues when during a break he looked at the ground and saw what it looked like a fossilised dinosaur egg. And that is how one of the largest egg-dinosaur sites in Europe was discovered.

From the science standpoint, we also heard about how hardshell eggs played a key part in the evolution of animals coming out of the sea, as they allowed reproduction on land, without having to return to water. There were (are) different strategies to take care of eggs, and spherical eggs mean that they were (are) buried. From fossil tracks, we know that the dinosaur females that laid their eggs in the area buried them for protection using their back legs. We saw two cast jackets too, ready for research, on display.

Collage showing several exhibits of the museum: two cast jackets (with fossils inside), the first sauropod egg excavated (of course, in broken pieces of shell pressed together), a dinosaur vertebra and a reproduction of a sauropod embryo in an egg.

Fossil eggs are categorised as oospecies, unless or until it can be proven which animal laid them. The Loarre dinosaur eggs are tentatively classified as Megaloolithus siruguei (sometimes spelt Megaloolithus sirugei), laid by a species of titanosaurian sauropod – some candidates are Garrigatitan, Ampelosaurus and Lohuecotitan. Sauropods were plant-eating dinosaurs that moved on four straight legs, and had long necks and tails, such as Dippy, the Diplodocus (and other copies, such as the one in Madrid or Paris). During the Cretaceous period, the dominant group of sauropods were the Titanosaurs, the last surviving long-necked dinosaurs until the extinction of dinosaurs – in South America there was Patagotitan; another example is Qunkasaura pintiquiniestra, which I saw in MUPA and MARPA exhibits.

The first dinosaur eggs ever registered were found in the Pyrenees – on the French side though – by Pierre Philippe Émile Matheron in 1846, and described in 1859 by Jean-Jacques Pouech. In 1967, Pierre Souquet documented dinosaur eggshells around the reservoir La Peña, some ten-ish kilometres from Loarre (had I known in 2021…). These were the same oospecies as the ones in Loarre – since the fossil layer is the same, it makes sense.

We were supposed to have a video-conference inauguration with someone from the university, but she decided to come in person, and that was moved to 19:00. So instead we hopped onto the vans that the organisation had provided and drove towards the geological formation called Mallos de Riglos, in the village of Riglos (hence the obvious name). The Mallos are a number of vertical domes conformed by reddish conglomerates. I had actually seen these geological structures before, from the other side of the River Río Gállego – not up close. The wording of the email “a slight ascent” had not made me suspect at first we were going to climb all the way up in the heat. Looking back, it was not that bad but a) I was not mentally prepared for it, and b) I have a new backpack, and it’s comfortable but… differently-shaped, so my centre of gravity was all off. There, Lope Ezquerro Ruiz (honourable mention to Manuel Pérez Pueyo, who cracked jokes and held the whiteboard) gave us a few good pointers on geology which made me wonder where he was when I was first studying geology at university.

Looking up at the Mallos de Riglos, vertical structures made from reddis conglomerates

Simply put, if one assumes that the natural laws have not changed with time (Uniformitarianism), then three things happen that define geology: strata deposits are horizontal, deeper strata are always older, and if they are not, it is because something new has eroded or deformed them. Of course, the Pyrenees mountain range is anything but flat.

Pyrenees geological structures on the side of the mountain, from the mountain opposite the river - erosive walls, faults and folds

On site, we learnt about the Garum facies, the result of the sedimentation of fluvial and marshy red clays. The layer started forming during the Maastrichtian (the latest age of the Upper Cretaceous, 72.2 to 66 million years ago. Both the Maastrichtian and the Cretaceous ended with a literal bang – the Cretaceous–Palaeogene extinction event, when non-avian dinosaurs went extinct, marked by the K-Pg boundary (formerly K-T boundary), a layer of sediment rich in iridium which probably came from a meteorite impact. The deposit of Garum facies continued through the first age of the Paleocene, the Danian. This means that the K-Pg boundary is somewhere inside the layer, which is pretty cool. And even cooler? There are dinosaur eggs there, obviously from before the mass extinction.

We learnt about this literally standing on the Garum itself. We talked about the time when the a lot of the Iberian Peninsula was a shallow sea with scattered islands, and then sat to try and “see” the processes of folding, faulting and erosion that created the Pyrenees mountain range as the African tectonic plate pushed against the Eurasian plate.

Reddish rock on the ground, called the garum facies

Every now and then, a vulture flew above us, in wide circles. We were apparently not appetising, because it flew away every time. Once we tackled the descent, we headed towards Ayerbe, where we split up for lunch. At 16:00 we met up again so professor Lope Ezquerro Ruiz could demonstrate how strata bend and break using a model and sand. Afterwards, we drove back to Loarre.

Griffon Vulture mid-flight

Walking down the Mallos de Riglos, with two vertical walls at the sides and a river-valley in the background

Simulation of how folding ocurs in rocks using sand

In the modern town hall, we had the first lecture of the afternoon, by José Luis Barco, Manager of the business Paleoymas, a company specialised in protection, development, management and use of cultural and environmental assets, with a strong emphasis on palaeontology and geology. One of their work lines is monetising projects related to palaeontology, as opposed to the “research-focused” stereotype. Between a palaeontological discovery and its communication or exploitation for the general public, there is a gap that can last over a decade.

Paleoymas is responsible for the project Paleolocal, which created the museum-lab in town, with the idea of studying the fossil eggs almost in situ, which would develop a touristic resource and help the village profit from it. The museum-lab is technically part of the Natural Science Museum Museo de Ciencias Naturales de Zaragoza, which has custody of the fossils according to the regional law. However, keeping the eggs in Loarre is a way to involve the community into protecting the palaeontological site, as well as to create a tourist flow to the village itself. See: yours truly, who spent 240 € in lodging there.

The second lecture was given by Miguel Moreno Azanza, who talked about the Theory of Excavating a Palaeontological Site, as one of the activities in the course was working on the field. The summary could be: “forget Alan Grant with a paintbrush, think hydraulic hammer”, but the important lesson is “do not dig up anything you cannot take with you, and register any and everything you see / do / touch”. Also, regarding egg shells, it’s important to write down whether you find them concave up or concave down. This can help decipher whether the egg has rolled or not (for example, if several eggs are found together, were they in a nest, or where they moved there somehow? Did a baby dinosaur break the eggshell?).

Around 19:30, we had the official inauguration of the course, with a representative from the university, Begoña Pérez, and the mayor of Loarre, Roberto Orós, who was nice enough to buy us all a drink afterwards. Not one to turn down a free Coke, I tagged along for a while, and when people started taking their leaves, I returned to my room. I had some crisps in lieu of dinner, took a long (and I mean long) shower, scribbled down some notes and lay down till it was time to sleep.

Palaeontological Restoration Techniques through the preparation of Loarre dinosaur eggs