The purpose of the digitisation of this collection, as part of the NHM Science Strategy, is securing the future of the collection making it accessible and digitally available, also engaging and involving the widest possible audience, reaching out nationally and globally, onsite and online. Most of the specimens were curated to the highest curation standards, replacing trays with acid-free ones for all the specimens and re-boxing them with plastazote for half of the specimens.

The curation and digitisation of this collection was funded by Museum internal funding. For this, a project was created estimating 3,000 specimens in this collection, being aware of the average number of specimens per drawer with fossil lithistids. The complete digitisation of the specimens resulted in 40% more specimens. Sometimes, the drawers had specimens which were not lithistids and were relocated to the right place. There were locations with a mixture of specimens (specimens for exhibitions, used in tours and/or student classes) where we had to discern which ones were lithistids and which ones belonged to other groups to relocate them.

There were 337 specimens without any registration number. We generated these and created the labels for these specimens and 400 further specimens which had only a yellow sticker with the registration number. We included all the labels in special transparent archival polyester sleeves and printed the new labels generated on special archival paper with archival ink.

The digitisation took up 62.5% of the time and, as the project timeline advanced, digitisation, reorganisation and curation were combined. To finish with data cleansing, the last two weeks were shared with curation and reorganisation of some specimens.

The digitisation involved recording all the written information documented on the specimen labels and/or the catalogue books when the specimens did not have associated labels or the data were incomplete. We also studied those publications where the specimens were cited, described and/or figured. For this, an Excel template compatible with Emu was built. In order to make sure about digitising lithistid taxa, we followed the Porifera Treatise (Finks et al. 2004) considering the Subclass Lithistida Schmidt, 1870 and papers on fossil lithistids. At the same time as the specimens were digitised, the taxonomic names were updated, by batches, after the most updated revisions. In the case of geographic and stratigraphic records, they were updated when they were recorded. Quality control and assurance procedures were implemented at all stages to avoid errors and repeating them.

Once all the data were recorded, the last few weeks were used for cleansing and standardising the data, including standardisation of acquisition details and their completeness, with the help of NHM books on donations/acquisitions and the World Palaeontological Collections book by Cleevely (1983). This stage helped us to correct the mistakes made.

The reorganisation of those sponges which were non-lithistids in their corresponding locations was carried out when we had most of the specimens databased and lasted half of the project timeline. The more specimens digitised, the easier it was to recognise those non-lithistid taxa and also find those missing specimens in the lithistid NHM locations. The non-lithistids were relocated to the right places in the Fossil Porifera Collection. Concerning the missing specimens, some appeared in other adjacent drawers or in drawers with mixed specimens from the collections used for students or for exhibitions. 200 missing lithistids were recorded on the dataset as the trays contained the labels, but not the specimens. Most of these specimens were found (90%) in other locations of the Porifera Collections.

Curation, including re-boxing with plastazote and acid free trays, was done with the help of four volunteers who worked at the same time as the collections were reorganised, digitised and the data cleansing done.

The project timeline prepared before the project execution was very useful to focus the project and take decisions.

A further stage in the digitisation of this collection will be to take images of those specimens which have not been imaged previously. This will help stakeholders with research and identification of lithistid specimens.

History of the Collection

This collection is compiled by purchases, donations and bequests of historical collectors, researchers and, more recently, NHM staff. About 37% of the collection has unrecorded history, but the remainder is mainly made up of small collections of less than 200 specimens (Fig. 3B) and from the largest to the smallest collections: the Claud William Wright Collection from the Cretaceous of England, donated between 1948 and 1949; the Anton Schrammen Collection from the Palaeozoic and Mesozoic of Sweden, Canada, USA, Germany, Poland, purchased between 1904 and 1938; the Arthur Walter Rowe Collection from the Cretaceous of England, purchased in 1926; the David J. Ward Collection from the Cretaceous of England donated in 1994; and the John Edward Lee Collection, from the Cretaceous and Silurian of different countries (England and Wales, UK; Germany; Canada and Sweden) presented in 1885 (Fig. 3A).

Figure 3.  

Origin of the NHM Fossil Lithistida Collection. A. The largest collections; B. Those minor collections shown in A.

The importance of this collection lies not only in its stratigraphic and geographic range, but also in the scientific value of its types and figured specimens to species and even subspecies/varieties that have not been revised since their original descriptions (126 taxa) (Suppl. material 2). Currently, there are taxa not recognised for the specimens identified to subspecies and variety levels. Recent studies have focused on biosilicification evolution in lithistids which may help to unlock the changing patterns in the silica cycle in the oceans through geological time (Conley et al. 2017).

The stratigraphic distribution plays an important role in this fossil collection. This is linked to the origin. As most of the collection comes from the UK, most is Cretaceous (81%). Other localities where the Cretaceous lithistids have representation in this Collection are in Europe, Australia, India, Libya and the Republic of Trinidad and Tobago. Ten percent is Jurassic, coming from Europe and mainly from UK-England. Silurian lithistids (5%) are mainly from Sweden and North America. In much less proportion is the Ordovician (2%) of Europe and North America. The Cambrian, Permo-Carboniferous, Triassic and Paleogene lithistids are represented scarcely from sites in Europe, Ukraine, Australia, Cyprus, Israel, UK (England, Wales and Scotland) and USA (Fig. 6).

Figure 6.  

Bubble map with fossil sponge sites by stratigraphy from specimens kept at the NHM.