Ancient Craniiform Brachiopod: A Newly Discovered Species with a Unique Shell Shape and Lifestyle
Scientists from HSE University, MSU, and Tallinn University of Technology have studied a fossil species of ancient brachiopods that lived in a warm sea in what is now northern Estonia more than 445 million years ago. These ancient brachiopods developed a cup-shaped shell with a protective 'cap' that shielded them from overgrowth by other marine organisms. The study has been published in Palaeogeography, Palaeoclimatology, Palaeoecology.
About 445 million years ago, the territory of present-day Estonia was covered by a warm, shallow sea. On its seafloor lived a tiny creature only a few millimetres long—a brachiopod called Pocillocrania rubeli. Despite its small size, this species had one of the most unusual shells among its relatives; it developed a cup-shaped shell with a protective 'cap.' A new study has shown that this distinctive shell evolved as an adaptation to living on the surface of bryozoan colonies.
Bryozoans are colonial aquatic animals that grow continuously by budding, gradually building a calcareous skeleton. If the ventral valve of the brachiopod, which was attached to the substrate, had remained flat—as it does in most species of this brachiopod group—the growing bryozoan colony would eventually have blocked its access to water and suspended food particles.
Both bryozoans and brachiopods generate feeding currents using their tentacles and capture suspended food particles from the water, thereby competing for the same resource. By rising above the surface of the colony, the brachiopod not only avoided overgrowth but also gained a more advantageous position for filter feeding.
'Interestingly, a modern relative of this fossil species—brachiopods of the genus Neoancistrocrania—also has a cup-shaped ventral valve. This species lives on corals, and this valve shape allows it to rise slightly above the surface of the growing colonial organism,' explains Elena Temereva, Professor at the Joint Department with RAS Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, HSE Faculty of Biology and Biotechnology.
The shape of the dorsal (upper) valve of the fossil brachiopod was equally unusual: while the ventral valve formed a deep bowl, the dorsal valve resembled a wide-brimmed sombrero slightly recessed into it. At the same time, the valves were movable and could open and close rapidly. When the dorsal valve was slightly raised, a gap formed between the two valves, allowing water to enter the mantle cavity. Inside was the lophophore, a filtering organ that circulates water and extracts food particles from it.
One of the most important results of the study was the reconstruction of the animal’s internal anatomy. Muscle imprints—among the few soft-tissue features that can be preserved in fossils—allowed the scientists to reconstruct almost the entire muscular system of this extinct brachiopod. It was found that this small species had five pairs of muscles controlling the movement of both the valves and the lophophore. The researchers suggest that valve opening was primarily driven by hydraulic pressure from internal body fluids. When the muscles contracted, the valves closed abruptly, likely serving as a defensive response to danger. In addition, auxiliary oblique muscles allowed the valves to rotate slightly relative to each other.
The researchers believe that these movements may have had a practical function. The hard shell surface likely attracted organisms seeking a substrate for attachment. Small rotations of the valves could have helped the brachiopod dislodge unwanted settlers before they had time to establish themselves, effectively shaking them off its skeleton. In addition, the scientists were able to reconstruct the position and structure of the lophophore.
By reconstructing the morphological features of brachiopods, scientists are gradually restoring the structure of entire ancient marine ecosystems.
'We do reconstructions not for their own sake but to understand how these organisms lived. Ideally, we would like to understand how ancient seas were structured, what processes occurred within them, and what the environment was like,' concludes Prof. Temereva.
See also:
Team Success: Aligning Means with Objectives
In corporations, sports, and academia, people often face challenges they cannot handle alone. In such cases, selecting the right team is crucial. Tatiana Mayskaya, Associate Professor at the HSE Faculty of Economic Sciences and the International College of Economics and Finance, together with colleagues from foreign universities, examined team characteristics and found that less diverse teams are better suited to objectives where a high average performance is important, whereas more diverse teams are preferable when avoiding failure is critical. The paper has been published in Economic Theory.
Economists Propose More Effective Approach to Reducing Smoking
Economists at HSE University have examined how smokers respond to changes in cigarette prices. When tobacco prices increase, cigarette consumption does not always decline. In fact, spending on tobacco may even rise: according to the researchers, a 1% decrease in cigarette affordability leads to a 0.28% increase in per capita tobacco expenditure. The findings suggest that to reduce smoking rates, tobacco prices must rise faster than household incomes. The study has been published in Voprosy Statistiki.
Biologists Discover Unique Properties of MiR-93-5p MicroRNA in Prostate Cancer
Researchers at the International Laboratory of Microphysiological Systems of the HSE Faculty of Biology and Biotechnology investigated how different isoforms of the same microRNA influence gene function in prostate adenocarcinoma. The study found that in some cases, microRNAs can reinforce each other’s effects by targeting and suppressing the same genes. This finding offers a fresh perspective on the molecular mechanisms underlying tumour development and on the search for disease biomarkers. The results have been published in PeerJ.
HSE Researchers Provide the World’s First Legal Definition of a Digital Ecosystem
Digital ecosystems have evolved from a technological innovation into a fundamental institution of the modern economy over the past few years. According to HSE University’s latest estimates, they account for 8.5% of Russia’s GDP. Previously, no jurisdiction had a statutory definition of what constitutes a digital ecosystem. HSE University researchers have addressed this gap by proposing the first legal concept of a digital ecosystem. Their article, ‘The Digital Ecosystem as a Novel Economic Phenomenon and Legal Concept,’ has been published in the BRICS Law Journal.
HSE Economists Use Search Queries to Forecast Birth Rates
Researchers from the HSE Faculty of Economic Sciences have shown that the accuracy of birth rate forecasts for Russia can be improved by almost 50% by incorporating the dynamics of online search queries related to pregnancy and childbirth into forecasting models. In the best-performing models, the forecasting error fell from 4.6% to 3.2%. The findings have been published in Populations and Economics.
When Looking at Their Own Faces, Men Forget Everything
In an experiment involving 15 healthy men, scientists at HSE University investigated how different phases of the cardiac cycle influence the excitability of the motor cortex when participants viewed either their own photograph or the faces of strangers. The researchers found that when participants looked at their own image, the brain’s response to signals from the heart was weaker, meaning that the influence of cardiac activity on the motor cortex decreased. This finding came contrary to expectations, as self-focused attention was thought to enhance the brain's sensitivity to internal bodily signals. The study has been published in Frontiers in Signal Processing.
HSE Researchers Discover Who Eats Out in Russia—And Why
Around one-third of Russians (31.3%) rarely eat out or buy ready-made meals. The core group of active consumers—those who eat out or purchase prepared food almost every day or several times a week—accounts for only about 9% of the population. These are the findings of a study conducted by the HSE Institute for Social Policy. According to the researchers eating out is no longer a marker of high social status in Russia.
Scientists Model How Interactions Between Societies Can Trigger Chaotic Behaviour
Scientists at HSE MIEM have proposed a mathematical model explaining how interactions between societies can influence their stability. Based on the classical theory of evolutionary games, the study reveals an unexpected effect: even a weak informational influence of one society on another can cause one society to remain stable while the other exhibits chaotic behaviour among its individual members. The study has been published in the International Journal of Bifurcation and Chaos.
Scientists Develop Bacterium-Sized Microlaser
An international team of researchers, including scientists from HSE University–St Petersburg, has developed microlasers that emit deep-ultraviolet light at a wavelength of 255 nanometres. The devices operate at room temperature, and the smallest of them measures just two micrometres in diameter—roughly the size of a bacterium. These microlasers could be used in sensors, spectroscopic systems, photonic chips, and communication devices. The paper has been published in Optics & Laser Technology.
HSE Develops App for Assessing Phonological Processing in Children
Researchers at the HSE Centre for Language and Brain have developed a new digital tool for assessing children's phonological processing skills—the ZARYA (Sound Analysis of the Russian Language) test battery. It is the first standardised application in Russia designed to provide a fast and reliable assessment of children's ability to distinguish speech sounds, retain them in working memory, and perform phonemic analysis. The app runs on Android tablets and smartphones and is available for download from RuStore. Details of the test validation have been published in the Journal of Speech, Language, and Hearing Research.