by Richard A. Fariña. Martín Batallés, Luciano Varela & P. Sebastián Tambusso
Departamento de Paleontología, Facultad de Ciencias, Montevideo and Sauce, Departamento de Canelones- Uruguay
In this post, we take advantage of our secondment to celebrate the works of prominent Barcelonans: the Salvador family, Antoni Gaudí and Jorge Wagensberg (to our dismay, we had to leave aside the deserved homages to other Catalonians, such as Salvador Dalí and Montserrat Caballé).
A collection with a South American twist
The Salvador collection is the main core of the Salvador Cabinet that is kept in the building of the Institut Botànic de Barcelona, in Montjuïc (https://scicomove.hypotheses.org/1080). This is an amazing product of a lineage of Barcelona apothecaries and naturalists who, from the beginning of the 17th century to the mid-19th century, assembled a very important library and scientific collections.
Among the curiosities, a distinctly South American guest catches the attention: an armadillo must have been seen as a mind-boggling exotism, an example of the prodigious diversity of the New World that offered the existence of a completely armoured mammal, able also to build underground galleries.
An architect that was not fond of Physics
It is widely known that Antoni Gaudí (1852-1926) was an innovator of architectural forms and construction techniques thanks to a rigorous and methodical work of geometric research. As a student, he had better qualifications in projects than in theoretical subjects.
For instance, he made a crucial advance in the historical imperative to build temples underscores the need for spacious, lofty structures. Temples must accommodate many people sharing a collective identity, with their height inspiring contemplation and perhaps awe of the divine. Early architectural technology allowed little more than horizontal beams between vertical columns until the progress of the Roman semicircular arch, which provided more dignified spaces for worship. Gothic architects elevated this further, constructing cathedrals over 100 metres tall, aiming at the proverbial skies. However, stability necessitated buttresses, compromising elegance and spirituality. It was Gaudí who introduced innovative catenaries, exemplified by the Sagrada Familia in Barcelona Wagensberg (2004). Among other buildings, that iconic cathedral benefitted from his mastery in resourcing into the catenary and soars vertically beyond 150 metres without lateral diversions, with your full attention thoroughly directed upwards.
And it is founded on tortoises (but not armadillos!), of course…

Fig. 1. Base of a column in the Sagrada Familia cathedral in Barcelona (Photo:
Bluffton.edu)
A kindest philosopher and physicist and museologist and…
Jorge Wagensberg (1948-2018) was professor, researcher, author as well as a finest human being. Born to Polish-Jewish parents who had relocated to Barcelona in the 1930s to escape persecution, he was multilingual, fluent in Yiddish, Catalan, Spanish, German, English, French and Italian. He was a prominent figure in the field of scientific communication, known for his work as an editor, lecturer, writer, and museologist. Among his most remarkable achievements, he created and directed the Science Museum in Barcelona (CosmoCaixa). As a scientist, he made significant contributions across various fields, including thermodynamics, theoretical biology, entomology and philosophy of science. He was also an accomplished author and editor and received several prestigious awards and honours. Here we are proud to follow is legacy by extending his approach on the size and shape effect of biological and human constructions.
Catenary
The catenary arch is the shape that a cable takes when it is hung from two points and only supports its own weight. If the load it supports is horizontally uniform, when it is hung from two points it adopts a parabolic shape. If it supports different point loads, the cable adopts the shape called funicular arch. (Gómez, 2002). Despite the optimal quality of the catenary arch in terms of resistance, for a long time it was considered to have an inelegant shape and difficult loading on the pillars. It was not used in traditional architecture, for which arch shapes were considered better. circular, elliptical, etc. However, Gaudí’s uniqueness consisted in applying the catenary arch spatially and creating the design model of the Church of Colonia Güell (Fig. 2) by means of some rope elements from which small bags of shot were hung that made it possible to obtain the load axes of each of the elements of the roof without using complicated mathematical calculations. By placing a cloth inside the model of the nave, he obtained the interior space and also the inverse of the work (Gómez, 2002).

Fig. 2. Multifunicular model of the church of Colonia Güell. (Photo:AA.VV., Gaudí 2002. Misceŀlània, Ed. Planeta, Barcelona (2002), author unknown)
This project did not come to its end, but this experience served the architect for his great project: the towers and the temple of the Sagrada Familia for which he used the same principles as in the catenary model of Colonia Güell (Bassegoda, 1999; Huerta, 2003; Bonet, 2004).
From the armadillo to the cathedral
For those that love statistics, here’s how a, the relevant variable that describes the depth of a catenary, varies with increasing body size in armoured mammals, from small armadillos to giant glyptodonts (Figs. 3 and 4).

Fig. 3. Glyptodon sculpture exhibited in the Museu de Ciències Naturals de Barcelona, Castell dels Tres Dragons (Photo: Martín Batallés).
Using logarithmical scale, that relationship proves to be linear. In other words, the larger the animal, the narrower the catenary.

Fig. 4. A reconstruction of an individual of Glyptodon and the catenary curve describing the curve of its carapace.
It would have been just right if this relationship was kept at the enormous weight of the cathedral. However, reality tends to be more complex: the difference in the supportive materials denies us the pleasure of the Platonical perfection. In any case, three different traditions are gathered in Barcelona to bring us the treasures hidden in scientific collections.

Fig. 5. Parameter b (describing depth in the catenary formula) for armoured Xenarthrans (y-axis) in regard to log body mass in kg (x-axis), including the regression curve, its equation and the correlation coefficient.
References
Bassegoda Nonell, J. y García Gabarró, G.: La Cátedra de Antoni Gaudí. Estudio analítico de su obra. Barcelona. Ediciones UPC. 1999.
Bonet, J. El Templo de la Sagrada Familia. Conferencia en la Fundación Politécnica de Cataluña. Barcelona. 2004.
Gaudí y la geometría de la naturaleza https://studylib.es/doc/88357/gaud%C3%AD-y-la-geometr%C3%ADa-de-la-naturaleza
Gómez Serrano, J. Arcos catenarios. En Gaudí, estudis técnics. Espai, geometría, estructura i construcció. Col.legi d’Arquitectes de Catalunya. págs. 97-102. Barcelona. 2002.
Huerta, S. 2003. El cálculo de estructuras en la obra de Gaudí. Ingeniería Civil 129: 121-133.
Wagensberg, J. (2004). La rebelión de las formas. Barcelona: Tusquets.
OpenEdition suggests that you cite this post as follows:
alexiacomte (November 15, 2023). Barcelona: armoured Xenarthrans and catenaries. SciCoMove — Scientific Collections on the Move. Retrieved February 19, 2026 from https://doi.org/10.58079/twv5