Parmi les arthropodes fossiles trouvés dans l'ambre, les scorpions se situent parmi les groupes les plus rares ; cependant, depuis environ deux décennies, plusieurs spécimens ont été décrits de l'ambre de la République dominicaine, du Mexique et de la Baltique. Les fossiles trouvés dans l'ambre de la République dominicaine et du Mexique sont étroitement associés aux scorpions actuels des régions antillaise et néotropicale. La position phylogénétique des scorpions dans l'ambre de la Baltique est cependant différente. Ces éléments peuvent être classés dans certaines lignées primitives actuelles de micro-buthidés. Cependant, les cinq spécimens décrits depuis 1996 correspondent tous à des genres nouveaux, distincts des genres actuels. Tout récemment, une découverte encore plus étonnante à été celle d'un fossile de l'ambre du Liban, le plus vieux connu (± 125–130 Ma) qui contienne des fragments biologiques. Une nouvelle famille, Archaeobuthidae Lourenço, a été créée pour ce spécimen également rattachée aux Buthoidea.

Le spécimen étudié à présent est le premier de l'ambre de Birmanie à être décrit ; il correspond au deuxième plus ancien exemplaire de scorpion trouvé dans l'ambre, quel qu'en soit le type (± 90 Myr), étant uniquement supplanté par Archaeobuthus estephani Lourenço 2001, décrit de l'ambre du Liban et daté d'environ 125–130 Ma.

Malgré l'état incomplet du spécimen, une étude détaillée autorise la description d'un nouveau genre et d'une nouvelle espèce. Les caractères diagnostiques définissant le nouveau genre Palaeoburmesebuthus sont les suivants : scorpions de petite taille (la taille totale des adultes peut être estimée à environ 10 mm) ; morphologie des parties observées, similaire à celle des Buthoidea ; anneaux du metasoma longs et aplatis, en particulier le cinquième ; carènes simples, mais bien marquées ; arc anal très simple, avec un seul lobe latéral ; telson très allongé, avec la vésicule fortement aplatie, à peine plus haute que le diamètre de la base de l'aiguillon, ce dernier étant pratiquement aussi long que la vésicule, très trapu à la base et avec sa partie distale très aiguë, les caractéristiques du telson étant diagnostiques du nouveau genre (Figure 1, Figure 2, Figure 3 and Figure 4).

Étant donné l'état très incomplet du spécimen étudié, il semble difficile d'assigner le nouveau genre à une famille précise au sein des Buthoidea. Pour cette raison, il est placé provisoirement dans une incertae familiae. Seule l'étude de nouveaux exemplaires pourra éventuellement justifier la création d'une nouvelle famille pour ce micro Buthoidea du Crétacé birman.

Scorpions are rare among the Arthropods fossilised in amber. Nevertheless, several specimens have recently been described from Dominican, Mexican and Baltic amber [3], [4] and [5]. Even though some of these descriptions may require confirmation, there is little doubt that the amber fossils found in Hispaniola and Mexico are closely related to the extant Buthidae of the Caribbean and Neotropical regions. The position of the Baltic amber scorpions is different, because the known specimens, which also belong to the family Buthidae, can be classified among some extant but primitive lineages of micro-buthids. Five of these specimens have been described in recent years and represent distinct new genera that can be associated only approximately with extant groups. Two other specimens, which were described during the last century, retain an enigmatic status. They can, however, almost certainly be regarded as belonging to the category of primitive micro-buthids [3], [4] and [5]. The history of amber scorpions, particularly those from the Baltic region, is complex. It has been described in detail by Lourenço and Weitschat [3], [4] and [5].

More recently, a remarkable scorpion fossil was described from Lebanese amber [2]. Lebanese amber is the oldest one known to contain biological fragments. A new family, Archaeobuthidae Lourenço, was created for this specimen, which can be classified among the Buthoidea.

Lebanese amber scorpions are much less common than those found in Baltic, Mexican or Caribbean amber. The type specimen of Archaeobuthus estephani Lourenço 2001 (family Archaeobuthidae) is not merely the first Lebanese amber scorpion to have been discovered, but is undoubtedly the oldest scorpion ever found in amber of any kind (± 125–130 Myr). The specimen described below is the first ever to have been found in Burmese amber, and is the second oldest amber fossil so far discovered (± 90 Myr). It is supplanted in age only by Archaeobuthus estephani Lourenço 2001.

The specimen investigated is trapped in a very clear block of yellowish amber that measures 7×6 mm and has been embedded in epoxy under vacuum [6]. The scorpion is rather incomplete, since the piece of amber had been broken. Only the metasoma with segments III, IV, V and telson are present. Both sides of the metasoma are clearly visible and allow detailed investigation.

According to Zherikhin and Ross [7], there is considerable confusion in the literature as to the probable age of Burmese amber. Also some confusion may exist regarding the precise sites in Myanmar from where the amber pieces originated. According to these authors there are five regions in Myanmar where fossil resins have been found, however Burmite only occurs in the Hukawng Valley. A synthesis of the geological data of the Hukawng Basin can be found in Zherikhin and Ross [7].

According to these authors, the presence of the foraminiferan Nummulites biarritzensis suggests a Middle Eocene (Upper Lutetian–Bartonian) age for the amber-bearing deposits, but the insects included in the Burmite suggest an older age for the amber. This could imply that the amber has been reworked, and some evidence can be found in the literature to support this. Therefore, from the evidence currently available, there appears to be two periods of deposition related to the amber bearing deposits in the Hukawng Valley. The first one took place during the Upper Cretaceous (Cenomanian), which is attested by the deposition of the Foraminiferan Orbitulina birmanica. For precise information on the geology of Burmese amber deposits, refer to Zherikhin and Ross [7].

Superfamily. Buthoidea C.L. Koch, 1837.

Family. Incertae familiae.

According to some of the characters proposed in the description – shape of the metasomal segments and telson, structure of carinae, and especially the presence of a simple anal arch with one lateral lobe – the specimen is unquestionably a member of the Buthoidea. The assignment to one of the three families presently accepted within the Buthoidea: Archaeobuthidae Microcharmidae and Buthidae is, however, complicated on account of the incompleteness of the specimen. Therefore, the new genus is assigned to an incertae familiae until further material becomes available.

It is important to notice that no extant buthoid genera have a telson morphology like that of the single Palaeoburmesebuthus. The reduced size of the vesicle in contrast with the very strong aculeus would suggest some kind of mechanical use in the technique of predation. This suggestion has already been discussed in the case of Archaeobuthus from Lebanese amber [2].

The new genus shares, with the Microcharmidae and some primitive buthids, a low evolutionary level. This places it in the first two gradients of the four/five that were defined by Lourenço [1] as being characteristic of genera of the Buthoidea. This situation is similar to that observed in Baltic amber scorpions [3], [4] and [5] and, in particular, to that observed for Archaeobuthus [2], suggesting that several more recent groups may have evolved since the Late Mesozoic and Early Cenozoic.